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A field study of worker productivity improvements
Applied
Ergonomics Vol26, No. 1, pp. 21-27, 1995 Copyright @ 1995 Ekvier Science Ltd Printed in Great Britain. All rights reserved tnm3-.%70/95 $10.00 + 0.00
A field study of worker productivity improvements Ashraf A. Shikdar Department of Safety Science, The University of New South Wales, Kensington, NSW, Australia
Biman Da:; Department of Industrial Engineering,
Technical Universiv of Nova Scotia, Halifax, NS, Canada
This paper describes the results of an experimental industrial field study conducted to improve worker productivity through various interventions in a repetitive production task performed under ergonomic working conditions. Worker productivity was found to improve most as a result of participative standard-setting with feedback and monetary incentives. In general, standard-settimlg with feedback, with or without monetary incentives, improved worker productivity. The performance without interventions was far below the normal standard. It was concluded that under good working conditions, challenge and incentives may be advantageously applied to improve worker productivity in industry. Keywords: worker productivity, production standard, production feedback, monetary incentive
The positive effects of ergonomics in improving worker productivity, safety and comfort are well recognized. However, providing ergonomic working conditions should be considered as the minimum requirement. Motivating workers for improved performance in industry, especially in repetitive production tasks, remains a major concern. These tasks are viewed as monotonous, boring and unmotivating, resulting in reduced worker product:ivity. Standard- or goal-setting and performance feedback are considered to have motivating effects on performance. Research studies have shown that hard goals produce better performance than no goals or easy goals (Locke, 1968; Kim and Hamner, 1976; Locke and Latham, 1984). Performance feedback has been found to be effective in increasing performance in overlearned repetitive tasks (Ammons, 1956; Leamon, 1974). Goal-setting wit’h feedback was found to be superior to goal-setting or feedback alone, and feedback was considered a necessary condition for goal-setting to be successful (Erez, 1977; Das, 1982; Locke and Latham, 1984). Goals are: typically assigned to operators, and are seldom set participatively with the operators. Research results often conflict regarding the superiority of participative goals over assigned goals in terms of performance (Latham and Yulk, 1975; Locke et al, 1981). Monetary incentive with or without goal-setting was found to improve performance in some cases (Locke, 1968; Locke and Latham, 1984). In laboratory studies, monetary incentive was found to have no effects on performance (Das, 1982; Das and Shikdar, 1990). The majority of the goal-setting studies noted above were conducted in laboratories. Only a limited
number of studies were performed in the field. However, these showed similar results to the laboratory studies (Fein, 1974; Locke et al, 1981; Locke and Latham, 1984). Most of the laboratory studies of goal-setting and feedback have several shortcomings. The tasks used were relatively simple or simulated. The goals were established arbitrarily or based on operators’ past performance. Measured standards, using work measurement techniques, were seldom used. The question of ‘how hard is hard?’ remained unresolved. Consideration was not given to the ergonomics of tasks or workplace design. Field studies had similar problems. Therefore, when attempts were made to apply these concepts in a real-life situation, the results were often conflicting (Das, 1982). The potential of standard-setting with performance feedback as major components of a job design approach has not been fully recognized at present. These concepts have not been utilized to a full extent in real-world task situations for improving worker productivity. In an attempt to study the effects of standard-setting in a more systematic manner, overcoming the shortcomings of the past studies, experiments were conducted on a more realistic task (drill press operation) in a university machine shop, using measured standards and ergonomics design principles. The provision of an assigned hard standard of 140% of normal, with feedback, produced maximum output, and a participative standard with feedback was inferior to an assigned 130% of normal standard with feedback (Das and Shikdar, 1989,199O; Shikdar and Das, 1992). However, this study was conducted in a university machine shop
21
22
A.A. Shikdar and R. Das
environment using college students, and the task duration was only for 1 h. It did not represent the reallife production situation where the employees are engaged for an 8 h work shift, and work in order to make a living. The outcomes of the study needed to be validated under real-life conditions. The main objective of the present study was to conduct an experiment in industry to reassess the outcomes of the laboratory study, using industrial workers and considering ergonomically designed working conditions.
The selected task was a fish-trimming operation. It involved trimming and sorting fish fillets into different product sizes. The trimming was done using regular trimming knives. The task was standardized so that the experiment would be conducted under the same working conditions and methods. An instruction sheet of the standardized task procedure was used (Figure I).
Methods
Workplace
Experimentation in industrial settings using industrial workers is highly complex, owing to real-life constraints. The experimental method of this study was designed and developed with the main objective of the research in mind and attempting minimal disruption to normal industrial production. The study was conducted in a section of a large fish-processing plant. The details of the experimental method are described elsewhere (Shikdar, 1991).
The production task was performed in a standing position. The workplace was designed considering ergonomics guidelines with respect to layout, posture and height. Combined male and female anthropometric data were used for this purpose (Das and Grady, 1983). A schematic layout of the workplace is shown in Figure 2. The work height was adjusted by the individual operators using special platforms. Only two of the production lines were prepared for the experiment.
Left hand Put the incoming pan of fillets to the pan holder from the supply belt. Pick up the pan from the pan holder and place it on the X-Ray Trim and Workstation 3. Sort out all the fillets and put them in the designated outgoing pans and defective fillet on the pan holder. 4. Put the empty pan on the pan return belt.
The task
layout
Right hand
Pick up the pan from the pan holder and place it on the X-Ray Trim and Workstation. 3. Sort out all the fillets and put them in the designated outgoing pans and defective fillet on the pan holder. 5. Get the knife for trimming.
6. Get the fillet from the pan holder. 7. Hold the fillet on the trimming board and prepare for trimming. a. Put the trimmed filled to the respective outgoing pans.
7. Trim off the defects and put aside the waste in the waste pan.
9. Clean the trim board and put aside the knife. (Repeat 1-9 for the next incoming pans until the outgoing pans are filled) 10. Put the outgoing pans on lower belt 10. Put the outgoing pans on lower belt
Figure 1
Operator instruction
sheet
A field study of worker productivity improvements
(normal standard X 1.4)) based on the laboratory study (Das and Shikdar, 1990). The participative standard was set by each individual operator in consultation with the experimenter. The operator was asked to set a standard above 100% normal that he/she thought was challenging and would like to attempt. Each standard was presented on a special feedback card for each individual operator in terms of lb/h against the standard.
Com~yor Belts
Performance
u S-F
on Symbols
I
I
I Knife Holder
Subjects
Figure 2 Schematic layout of the trimming workstation Work environment The physical environment
with regard to temperature, humidity and light was within normal levels (Sanders and McCormick, 1988). The temperature was 20 “C, relative humidity 50%, and light 2000 lx on the trim table. Owing to wet conditions the subjects wore fulllength aprons and special boots, covering up to the knees, and performed the task standing on a platform. As the sound level was above 85 dBA, the subjects used earplugs. Continuous water supply was provided for washing hands or filllets, if required. Overall, given the nature of the work, the physical working conditions in the plant were satisfactory. Production
feedback
A special feedback card was prepared for each operator who received feedback of results. Feedback was provided in terms of production output (lb/h) and performance (% of standard achieved) every 2 h. The performance for each working day was recorded on the card in graphical form for easy visualization. An example of the card is shown in Figure 3.
size
1
23
Forty-eight operators (trimmers), from among the regular employees, were selected on a voluntary basis as subjects for the experimental research. The criteria of screening were based on their having at least six months’ on-the-job experience, at least seventh-grade education, and on their not planning to quit the job within a year. The subjects were paid in the usual manner (company wage rate) except for monetary incentive groups, who were paid on an incentive basis at 1:0.6 (i.e. for a 1% increase in performance 0.6% increase in pay), which was company policy. The participants were given adequate demonstration and instruction before starting the experiment. To familiarize them with the standardized method of task performance, they were given training for one day. The subjects performed the same task in the experimental sessions under specific experimental conditions.
standard
The proper motions to perform the task were established through methods-time measurement (MTM) and ergonomics analysis. The normal time to process a pan of fish fillets (20 lb, 9 kg) was determined through MTM, and a stopwatch time study was made to check the accuracy of the MTM standard (Barnes, 1980). The standard time was calculated using the formula Standard time = Normal time (1 + Allowance in percent)
(1)
A 17% allowance, comprising 7% for unavoidable delays, 5% for fatigue and 5% for personal needs, was added for the particular task, taking into consideration the wet working conditions. The normal production (100% normal) was calculated in terms of the number of lb of fillets to be processed per hour. For example: normal time to process one pan (20 lb) of fillets = 4.5 min, standard time = 4.5 (1 + 0.17) = 5.27 min, normal production standard = 20/5.27 X 60 = 227.70 lb/h. The details of calculation are presented elsewhere (Shikdar, 1991). The hard standard was established on the basis, that, in an incentive plan witlh manual tasks, workers could perform up to a pace of 200% (Konz, 1987), and for this study it was taken to be 140% of the normal standard
Worker productivity
Worker productivity in terms of quantity output (lb/h, fillet trimmed) and performance (% of normal standard achieved) was measured every 2 h. The full day’s output was converted to performance per hour in the percentage of normal standard achieved, for statistical analysis. Experimental
design
The subjects were assigned randomly
into six groups and the six experimental conditions were randomly assigned to the groups. The experimental conditions and assignment of groups to these conditions are presented in Table 1. The experimental conditions for each group were explained to its members. The subjects of each group performed one training and ten experimental sessions, each session being a full day’s work, over a 10 month period. Only one session was held on one day for only one group and the sessions were assigned in random. In every session the subjects of the group were reminded about their experimental condition. The subjects of Group 1 (control group) were simply asked to do their best. All the participants were asked not to discuss their experiments and results with each other.
A. A. Shikdar and B. Das
24
Day6
Figure 3 An example Table 1 Characteristics
Day8
Day9
Day IO 1 -t \vlwkillg Da,r 1
card
groups
Table 2 Analysis of variance (ANOVA) of worker production data
output
Production standard (PS)
Monetary Performance incentive feedback (PF) (MI)
Source
df
MS
F
PR > F”
rZb
2114.13 414.23
0.38
No PF
Assigned Assigned Participative Assigned Participative
PS: PS: PS: PS: PS:
PF PF PF PF PF
5 42 47
0.01
No PS
Groups Errors Total
5.10
Control
Group 1 2 3 4 5 6
of the experimental
of feedback
(
Day7
100% normal 140% of normal Participative 140% of normal Participative
No No No No MI MI
MI MI MI MI
“PR > F = Probability that a random or equal to the observed value b? = Coefficient of determination Table 3 Analysis output data
Results The production output data were collected in terms of percentage of the normal standard, for statistical analysis. The data were analysed through the use of the Statistical Analysis System (SAS) computer program (Ray, 1982). Analysis of variance (ANOVA), analysis of covariance (ANOCOVA) and the Student NewmanKuel’s (SNK) range test were employed for the analysis. The results of the ANOVA (Table 2) showed that differences between the six groups were highly significant (F = 10, p < 0.01) in terms of production output. It was believed that the initial or inherent ability of the subjects might have conditioned the outcome of the experimental results. To allow for this individual variation between the subjects of the groups, an analysis of covariance was performed on the data using the training data as the covariate. Thus an attempt was made to achieve statistical control of the errors by the removal of the influence of the individual differences. The results of the ANOCOVA (Table 3) showed that the differences between the groups were still highly significant (F = 7.67, p < 0.01) but that the covariate was also highly significant, indicating that the operator’s inherent capability had a considerable bearing on his or her performance. The adjusted means of production output of each group were calculated on the basis of the ANOCOVA and using the following formula: Ya,j = Yunadj-
b(Z - 2)
(2)
of covariance
F value would be greater
(ANOCOVA)
of worker production
Source
df
MS
F
PR > F”
Groups Covariate Errors Total
5 1 41 47
2114.13 5975.02 278.60
7.59 21.45
0.01 0.01
“PR > F = Probability that a random or equal to the observed value ‘? = Coefficient of determination .
than
1
F value would be greater
r 2a
0.60
than
where Y,dj and Y”nadj are adjusted and unadjusted group means, b = pooled within-class regression coefficient between each individual or subject’s experimental (unadjusted) and traiging (covariate) values for all the subjects, and X and X are training or covariate group and grand (for all groups) means respectively. The adjusted group means are presented in Table 4 and the percentage increases or decreases in performance are presented in Table 5. Figure 4, drawn with the adjusted means, shows the production output of the groups by day. The trends in performance of each group can be visualized from this figure. The adjusted means were used for the subsequent SNK range test for comparative analysis of the groups. The results of the SNK range test are presented in Table 6. Normal
production
standard
A comparison between Group 2 (100% normal and feedback) and Group 1 (control: no standard and no
A field study of worker productivity improvements Table 4 Adjusted group means of performance
(%)
feedback) showed that the assignment of a normal production standard with feedback of results improved the operator’s performance output significantly (p C 0.01). The increase in production output was about 12% compared with the control group. The result was not consistent with the laboratory study, where no significant difference was found between these conditions. The provision of a normal production standard along with feedback in real industry jobs was superior to no standard and no feedback or a simple ‘do your best’ standard.
Group
:Control)
13.63
2 (PS: 100% + PF)
3 (PS: 140% + PF
4 (PS: Partic. + PF)
5 (PS: 140% + MI)
6 (PS: Partic. + PF+MI)
82.82
90.18
107.38
103.43
116.25
increase or decrease in performance
Table 5 Percentage
Comparison 2 3 3 4 4 5 5 6 6 6
% increase in performance
between groups
(Assigned normal) vs 1 (Control) (Assigned hard) vs 1 vs2 (Participative) vs 1 vs 3 (Assigned hard + MI) vs 1 vs 3 (Participative + MI) vs 1 vs 4 vs 5
Assigned
hard production
140
Participative
x Gr. 1 (Conuol)
q
Gr. 2 (PS: Gr. 3 (l’s: Gr. 4 (PS: Gr. 5 (PS:
’
Gr. 6 (PS: Pticip.+PF+MI)
1
Figure
2
4 Production
3
4.
output
Groups 1 2 3 5 4 6
6
of groups
Table 6 Student Newman-Kuel’s Groups/differences
5
lOO%+PF) 140%+PF) Particip.+PF) .140%+PF+M9
7
8
9
10
by days
(SNK) range test for worker production
in adjusted
1 (Control)
2 (PS: MO% + PF)
-
9.19** -
production
standard
The subjects of the participative groups set themselves a standard of about 120% of normal on the average. A compqison between Group 4 (participative and feedback) and Group 1 (Control) revealed that the provision of a participative standard with feedback significantly improved worker performance. The increase in production output was about 46% compared with the control group. A comparison between Groups 4 and 3 (assigned hard) showed that the production output of the participative standard group was superior to that of the assigned hard standard group. Stated otherwise, the provision of a participative standard with feedback led to better performance than did an assigned hard standard of 140% of normal with feedback. The difference was about 19% in production output. The result was contrary to the laboratory study, in which the assigned hard standard of 140% of normal with feedback was significantly better in terms of production output than the participative standard with
80
A *
standard
A comparison between Group 3 (assigned 140% of normal and feedback) and Group 1 (Control) showed that the provision of an assigned hard standard and feedback had a highly significant positive effect on worker performance. The increase in production output was about 22% compared with the control group. The production output of Group 3 was significantly better than the production output of Group 2 (assigned normal). The increase was about 9%. This result was consistent with the result of the laboratory study. All the subjects accepted the hard standard. Probably, they found the job challenging and were motivated by the specific hard standard and feedback. From this it could be stated that a hard standard and feedback can improve worker productivity significantly compared to the normal standard and feedback.
12.48 22.48 8.89 45.83 19.07 40.47 14.69 51.88 8.26 12.39
l
25
output data
means between group@ --)
;PS: 140% + PF)
&:
140% + PF + MI
16.55** 7.36* -
29.80** 20.61** 13.25** -
aGroups in order of increasing differences in adjusted means (production *p < 0.05 (significant), **p < 0.01 (highly significant) Note: Adjusted production output for Group 1 (Control) = 73.63%
4 (PS: Participat. 33.75** 24.56’* 17.20** 3.95 -
output,
% of normal)
+ PF)
6 (PS: Part. + PF + MI) 42.62** 33.43** 26.07** 12.82** 8.87* -
26
A.A.
Shikdar and B. Das
feedback. Although the participative standard was set at a much lower level (on average) than the assigned hard standard, the worker production output was much higher. This indicates that in real settings a participative standard is preferred and people work harder to reach their own standard. Monetary
incentive
Monetary incentive was provided to the assigned hard (140% of normal) group (Group 5) and a participative standard with feedback group (Group 6) to determine whether monetary incentive would improve worker performance further. A comparison between Group 5 (140% of normal + feedback + monetary incentive) and Group 3 (140% of normal + feedback) revealed that the provision of monetary incentive along with the assigned hard standard and feedback further improved worker performance significantly. The improvement in production output for Group 5 was about 15% greater than Group 3 (Table 5). A comparison between Group 6 (participative + feedback + monetary incentive) and Group 4 (participative + feedback) showed that the provision of monetary incentive along with the participative standard and feedback resulted in significantly higher performance than the provision of participative standard with feedback only. The increase in production output for Group 6 was about 8% compared with Group 4. Stated otherwise, the provision of monetary incentive had a significant positive effect on worker performance. Compared with the control group, the improvements were about 58% for the participative standard with feedback and monetary incentive (Group 6) and 40% for the assigned hard standard (140%) with feedback and monetary incentive (Group 5). Monetary incentive did not have any effect when provided with an assigned hard standard (140%) and feedback in the laboratory studies conducted earlier. Discussion This study was conducted in a large fish-processing plant with a trimming task, as opposed to the drill-press operation in the previous laboratory study. Although the tasks were different, the methodology of these experiments remained very similar. It is evident that the results of the industrial study are different from the laboratory study in many aspects. Laboratory research has some inherent limitations, especially when human subjects are involved. The population sample and the work situation were not representative of the real-life work situation. In the present industrial study, the subjects were industrial workers, who worked in a real-life work situation and engaged in a normal 8 h work shift. However, the problems of conducting research in a real-life task situation should be recognized. Generally, industries are not interested in research or experimentation and would rather use strategy that others have previously found beneficial. Also, workers generally do not like to be studied. These problems were resolved by convincing both the union and management, through meetings and seminars, that the study would be beneficial to both parties and that any positive findings could be applied in the future to improve worker productivity in repetitive production tasks. It was clearly explained that the study
would be conducted without much disruption in usual production activities. An assigned normal production standard (100%) with feedback did not show any effect in the laboratory situation in terms of production output, but its effect was significant in the industrial situation. The specific normal standard with feedback was considered a substantial change in the work situation, sufficient to cause an improvement in worker performance. An assigned hard standard of 140% of normal, with feedback, was found to be the optimum standard condition in terms of production output in the laboratory settings. In the field study the improvement in production output was also significant compared with assigned normal standard with feedback, but this was not the optimum standard condition in industry. In the laboratory situation, the subjects who were assigned hard standards (140%) outperformed the subjects who had set their own standards. This result was reversed in industry. The performance of the participative standard with feedback condition was significantly better than the performance with the assigned hard standard of 140% and feedback. The operators probably perceived the assigned hard standard to be difficult and did not work harder, as there was no monetary gain. However, when the subjects set their own standards, they tried to reach the standard even though they had set relatively hard standards. The provision of a participative standard not only motivated them to work harder, but also reduced the pressure to reach a high standard. The difference in populations, student subjects in the laboratory versus industrial workers in the field, was probably mainly responsible for such outcomes. Monetary incentive in the laboratory situation did not have any effect on performance. It was speculated that as the scope to earn a substantial amount of money for the short time was limited (for student subjects) there was no further improvement due to monetary incentive. In industry, however, a monetary incentive had a significant effect on performance. In real life the workers have to make a living to maintain their quality of life. The results of this field study will have significant implications for industries where industrial managers are concerned with worker productivity improvement in repetitive tasks. There was no complaint of any adverse health effects from operators who had worked at a faster pace in assigned hard and participative standards conditions, although it was beyond the scope of the present research actually to measure the health effects. Conclusions On the basis of the results obtained in this particular industrial setting, the following conclusions are drawn.
(1) The (2)
provision of an assigned normal production standard (100% normal) with feedback improves worker productivity significantly. An assigned hard standard of 140% of normal with feedback of results, and a participative standard with feedback, improved worker productivity in industry significantly, compared with the provision
A field study of worker productivity improvements
of an assigned norm.al standard with feedback. A participative standard with feedback was, furthermore, superior to the assigned hard standard with feedback in terms of worker productivity. incentive along with (a) an assigned (3) Monetary hard standard and feedback of results and (b) a participative standard with feedback, further improved worker productivity. The participative standard with feedback and monetary incentive proved to be the best standard condition in industry. The improvement in performance was about 58% compared with the control condition. standards, performance feedback and (4) Production monetary incentives proved to be important job factors, as they significantly affected task performance. Participation of workers in setting standards should be considered an important factor in industry, especially in a unionized environment. (5) For maximum worker productivity improvements, a participative standard with feedback and a monetary incentive could be employed in industry for a repetitive production task under ergonomically designed working conditions. This may have the effect of somewhat increasing challenge and interest. Monetary incentives could be a viable approach for a continued employee commitment. To implement the positive outcomes of this research, the following future rese.arch is recommended. (1) The results of the study, and specifically the best standard condition., should be applied on a continuous basis for a longer period to investigate whether the effects would be sustained. (2) The possibility of adverse effects on health, especially cumulative trauma disorders (work-related upper limb disorders) as a result of working at a faster pace for a long time, needs to be investigated. attitudes and satisfaction under these (3) Worker circumstances need to be assessed.
Acknowledgements The authors would like to thank the management and employees of the ‘High Liner’ National Sea Products Ltd, Canada, for their facilities and participation, and the SSH Research Council of Canada for funding the research.
27
References R.B. 1956 ‘Effects of knowledge of performance: a survey and tentative theoretical formulation’ J. Gen Psychol 54, 179-299 Barnes, R.M. 1980 Motion and Time Study: Design and Measurement of Work 7th edn, John Wiley Das, B. 1982 ‘Effects of production feedback and standards on worker productivity in a repetitive production task’ IIE Tram
Ammons,
14( 1), 27-37 Das, B. and Grady,
R.M. 1983 ‘Industrial workplace layout design: an application of engineering anthropometry’ Ergonomics 26(5),
433-447 Das. B. and Shikdar,
A.A. 1989 ‘Assigned and participative production standards and feedback affecting worker productivity in a repetitive manufacturing task’ J Hum Ergo1 18(l), 3-12 Das, B. and Shikdar, A.A. 1990 ‘Applying production standards and feedback to improve worker productivity and satisfaction in a reoetitive oroduction task’ IIE Tram 22(2), 124-132 Erez: M. 1577 ‘Feedback: a necessary condition for goal settingperformance relationships’ J Appl Psychol, 62(S), 624-627 Fein, M. 1974 Rational Approaches to Raising Productivity National Institute of Industrial Engineers, Norcross, Georgia Kim, J.S. and Hamner, W.C. 1976 ‘Effects of performance feedback and goal setting on productivity and satisfaction in an organisational setting’ .I Appl Psychol61(1), 48-57 Konz, S. 1987 Work Design: Industrial Ergonomics 2nd edn, Publishing Horizons Inc., Ohio Latham, G.P. and Yulk, G.A. 1975 ‘A review of research on the ;;.q&u5ion of goal setting in organisation’ Acad Manage .I 18, Leamon, T.B. 1974 ‘An investigation into the effects of knowledge of results on operator performance’ Ergonomics 15(S), 639-650
Locke, E.A. 1968 ‘Toward a theory of task motivation and incentives’ Organ Behav Hum Perform 3, 157-189 Locke, E.A. and Latham, G.P. 1984 Goal Setting: A motivational technique that works! Prentice-Hall Inc., NJ Locke, E.A., Shaw, K.N., Saari, L.M. and Latham, G.P. 1981 ‘Goal setting and task performance: 1968-1980’ Psycho1 Bull 90(l), 125-
152 Sanders, M.S. and McCormick, E.J. 1988 Human Factors in Engineering and Design 5th edn, McGraw-Hill, New York Ray, A.A. (ed.) 1982 SAS User Guide: Statistics SAS Institute Inc.,
Carry, NC A.A. 1991 ‘An investigation on the application of production standards, production feedback and monetary incentive in industry’, PhD Thesis, Department of Industrial Engineering, Technical University of Nova Scotia, Canada Shikdar, A.A. and Das, B. 1992 ‘The effects of assigning progressively harder production standards with feedback on worker productivity and satisfaction’ Znt .I Hum Factors Manuf 2(4), 325Shikdar,
337
Ergonomics Vol26, No. 1, pp. 21-27, 1995 Copyright @ 1995 Ekvier Science Ltd Printed in Great Britain. All rights reserved tnm3-.%70/95 $10.00 + 0.00
A field study of worker productivity improvements Ashraf A. Shikdar Department of Safety Science, The University of New South Wales, Kensington, NSW, Australia
Biman Da:; Department of Industrial Engineering,
Technical Universiv of Nova Scotia, Halifax, NS, Canada
This paper describes the results of an experimental industrial field study conducted to improve worker productivity through various interventions in a repetitive production task performed under ergonomic working conditions. Worker productivity was found to improve most as a result of participative standard-setting with feedback and monetary incentives. In general, standard-settimlg with feedback, with or without monetary incentives, improved worker productivity. The performance without interventions was far below the normal standard. It was concluded that under good working conditions, challenge and incentives may be advantageously applied to improve worker productivity in industry. Keywords: worker productivity, production standard, production feedback, monetary incentive
The positive effects of ergonomics in improving worker productivity, safety and comfort are well recognized. However, providing ergonomic working conditions should be considered as the minimum requirement. Motivating workers for improved performance in industry, especially in repetitive production tasks, remains a major concern. These tasks are viewed as monotonous, boring and unmotivating, resulting in reduced worker product:ivity. Standard- or goal-setting and performance feedback are considered to have motivating effects on performance. Research studies have shown that hard goals produce better performance than no goals or easy goals (Locke, 1968; Kim and Hamner, 1976; Locke and Latham, 1984). Performance feedback has been found to be effective in increasing performance in overlearned repetitive tasks (Ammons, 1956; Leamon, 1974). Goal-setting wit’h feedback was found to be superior to goal-setting or feedback alone, and feedback was considered a necessary condition for goal-setting to be successful (Erez, 1977; Das, 1982; Locke and Latham, 1984). Goals are: typically assigned to operators, and are seldom set participatively with the operators. Research results often conflict regarding the superiority of participative goals over assigned goals in terms of performance (Latham and Yulk, 1975; Locke et al, 1981). Monetary incentive with or without goal-setting was found to improve performance in some cases (Locke, 1968; Locke and Latham, 1984). In laboratory studies, monetary incentive was found to have no effects on performance (Das, 1982; Das and Shikdar, 1990). The majority of the goal-setting studies noted above were conducted in laboratories. Only a limited
number of studies were performed in the field. However, these showed similar results to the laboratory studies (Fein, 1974; Locke et al, 1981; Locke and Latham, 1984). Most of the laboratory studies of goal-setting and feedback have several shortcomings. The tasks used were relatively simple or simulated. The goals were established arbitrarily or based on operators’ past performance. Measured standards, using work measurement techniques, were seldom used. The question of ‘how hard is hard?’ remained unresolved. Consideration was not given to the ergonomics of tasks or workplace design. Field studies had similar problems. Therefore, when attempts were made to apply these concepts in a real-life situation, the results were often conflicting (Das, 1982). The potential of standard-setting with performance feedback as major components of a job design approach has not been fully recognized at present. These concepts have not been utilized to a full extent in real-world task situations for improving worker productivity. In an attempt to study the effects of standard-setting in a more systematic manner, overcoming the shortcomings of the past studies, experiments were conducted on a more realistic task (drill press operation) in a university machine shop, using measured standards and ergonomics design principles. The provision of an assigned hard standard of 140% of normal, with feedback, produced maximum output, and a participative standard with feedback was inferior to an assigned 130% of normal standard with feedback (Das and Shikdar, 1989,199O; Shikdar and Das, 1992). However, this study was conducted in a university machine shop
21
22
A.A. Shikdar and R. Das
environment using college students, and the task duration was only for 1 h. It did not represent the reallife production situation where the employees are engaged for an 8 h work shift, and work in order to make a living. The outcomes of the study needed to be validated under real-life conditions. The main objective of the present study was to conduct an experiment in industry to reassess the outcomes of the laboratory study, using industrial workers and considering ergonomically designed working conditions.
The selected task was a fish-trimming operation. It involved trimming and sorting fish fillets into different product sizes. The trimming was done using regular trimming knives. The task was standardized so that the experiment would be conducted under the same working conditions and methods. An instruction sheet of the standardized task procedure was used (Figure I).
Methods
Workplace
Experimentation in industrial settings using industrial workers is highly complex, owing to real-life constraints. The experimental method of this study was designed and developed with the main objective of the research in mind and attempting minimal disruption to normal industrial production. The study was conducted in a section of a large fish-processing plant. The details of the experimental method are described elsewhere (Shikdar, 1991).
The production task was performed in a standing position. The workplace was designed considering ergonomics guidelines with respect to layout, posture and height. Combined male and female anthropometric data were used for this purpose (Das and Grady, 1983). A schematic layout of the workplace is shown in Figure 2. The work height was adjusted by the individual operators using special platforms. Only two of the production lines were prepared for the experiment.
Left hand Put the incoming pan of fillets to the pan holder from the supply belt. Pick up the pan from the pan holder and place it on the X-Ray Trim and Workstation 3. Sort out all the fillets and put them in the designated outgoing pans and defective fillet on the pan holder. 4. Put the empty pan on the pan return belt.
The task
layout
Right hand
Pick up the pan from the pan holder and place it on the X-Ray Trim and Workstation. 3. Sort out all the fillets and put them in the designated outgoing pans and defective fillet on the pan holder. 5. Get the knife for trimming.
6. Get the fillet from the pan holder. 7. Hold the fillet on the trimming board and prepare for trimming. a. Put the trimmed filled to the respective outgoing pans.
7. Trim off the defects and put aside the waste in the waste pan.
9. Clean the trim board and put aside the knife. (Repeat 1-9 for the next incoming pans until the outgoing pans are filled) 10. Put the outgoing pans on lower belt 10. Put the outgoing pans on lower belt
Figure 1
Operator instruction
sheet
A field study of worker productivity improvements
(normal standard X 1.4)) based on the laboratory study (Das and Shikdar, 1990). The participative standard was set by each individual operator in consultation with the experimenter. The operator was asked to set a standard above 100% normal that he/she thought was challenging and would like to attempt. Each standard was presented on a special feedback card for each individual operator in terms of lb/h against the standard.
Com~yor Belts
Performance
u S-F
on Symbols
I
I
I Knife Holder
Subjects
Figure 2 Schematic layout of the trimming workstation Work environment The physical environment
with regard to temperature, humidity and light was within normal levels (Sanders and McCormick, 1988). The temperature was 20 “C, relative humidity 50%, and light 2000 lx on the trim table. Owing to wet conditions the subjects wore fulllength aprons and special boots, covering up to the knees, and performed the task standing on a platform. As the sound level was above 85 dBA, the subjects used earplugs. Continuous water supply was provided for washing hands or filllets, if required. Overall, given the nature of the work, the physical working conditions in the plant were satisfactory. Production
feedback
A special feedback card was prepared for each operator who received feedback of results. Feedback was provided in terms of production output (lb/h) and performance (% of standard achieved) every 2 h. The performance for each working day was recorded on the card in graphical form for easy visualization. An example of the card is shown in Figure 3.
size
1
23
Forty-eight operators (trimmers), from among the regular employees, were selected on a voluntary basis as subjects for the experimental research. The criteria of screening were based on their having at least six months’ on-the-job experience, at least seventh-grade education, and on their not planning to quit the job within a year. The subjects were paid in the usual manner (company wage rate) except for monetary incentive groups, who were paid on an incentive basis at 1:0.6 (i.e. for a 1% increase in performance 0.6% increase in pay), which was company policy. The participants were given adequate demonstration and instruction before starting the experiment. To familiarize them with the standardized method of task performance, they were given training for one day. The subjects performed the same task in the experimental sessions under specific experimental conditions.
standard
The proper motions to perform the task were established through methods-time measurement (MTM) and ergonomics analysis. The normal time to process a pan of fish fillets (20 lb, 9 kg) was determined through MTM, and a stopwatch time study was made to check the accuracy of the MTM standard (Barnes, 1980). The standard time was calculated using the formula Standard time = Normal time (1 + Allowance in percent)
(1)
A 17% allowance, comprising 7% for unavoidable delays, 5% for fatigue and 5% for personal needs, was added for the particular task, taking into consideration the wet working conditions. The normal production (100% normal) was calculated in terms of the number of lb of fillets to be processed per hour. For example: normal time to process one pan (20 lb) of fillets = 4.5 min, standard time = 4.5 (1 + 0.17) = 5.27 min, normal production standard = 20/5.27 X 60 = 227.70 lb/h. The details of calculation are presented elsewhere (Shikdar, 1991). The hard standard was established on the basis, that, in an incentive plan witlh manual tasks, workers could perform up to a pace of 200% (Konz, 1987), and for this study it was taken to be 140% of the normal standard
Worker productivity
Worker productivity in terms of quantity output (lb/h, fillet trimmed) and performance (% of normal standard achieved) was measured every 2 h. The full day’s output was converted to performance per hour in the percentage of normal standard achieved, for statistical analysis. Experimental
design
The subjects were assigned randomly
into six groups and the six experimental conditions were randomly assigned to the groups. The experimental conditions and assignment of groups to these conditions are presented in Table 1. The experimental conditions for each group were explained to its members. The subjects of each group performed one training and ten experimental sessions, each session being a full day’s work, over a 10 month period. Only one session was held on one day for only one group and the sessions were assigned in random. In every session the subjects of the group were reminded about their experimental condition. The subjects of Group 1 (control group) were simply asked to do their best. All the participants were asked not to discuss their experiments and results with each other.
A. A. Shikdar and B. Das
24
Day6
Figure 3 An example Table 1 Characteristics
Day8
Day9
Day IO 1 -t \vlwkillg Da,r 1
card
groups
Table 2 Analysis of variance (ANOVA) of worker production data
output
Production standard (PS)
Monetary Performance incentive feedback (PF) (MI)
Source
df
MS
F
PR > F”
rZb
2114.13 414.23
0.38
No PF
Assigned Assigned Participative Assigned Participative
PS: PS: PS: PS: PS:
PF PF PF PF PF
5 42 47
0.01
No PS
Groups Errors Total
5.10
Control
Group 1 2 3 4 5 6
of the experimental
of feedback
(
Day7
100% normal 140% of normal Participative 140% of normal Participative
No No No No MI MI
MI MI MI MI
“PR > F = Probability that a random or equal to the observed value b? = Coefficient of determination Table 3 Analysis output data
Results The production output data were collected in terms of percentage of the normal standard, for statistical analysis. The data were analysed through the use of the Statistical Analysis System (SAS) computer program (Ray, 1982). Analysis of variance (ANOVA), analysis of covariance (ANOCOVA) and the Student NewmanKuel’s (SNK) range test were employed for the analysis. The results of the ANOVA (Table 2) showed that differences between the six groups were highly significant (F = 10, p < 0.01) in terms of production output. It was believed that the initial or inherent ability of the subjects might have conditioned the outcome of the experimental results. To allow for this individual variation between the subjects of the groups, an analysis of covariance was performed on the data using the training data as the covariate. Thus an attempt was made to achieve statistical control of the errors by the removal of the influence of the individual differences. The results of the ANOCOVA (Table 3) showed that the differences between the groups were still highly significant (F = 7.67, p < 0.01) but that the covariate was also highly significant, indicating that the operator’s inherent capability had a considerable bearing on his or her performance. The adjusted means of production output of each group were calculated on the basis of the ANOCOVA and using the following formula: Ya,j = Yunadj-
b(Z - 2)
(2)
of covariance
F value would be greater
(ANOCOVA)
of worker production
Source
df
MS
F
PR > F”
Groups Covariate Errors Total
5 1 41 47
2114.13 5975.02 278.60
7.59 21.45
0.01 0.01
“PR > F = Probability that a random or equal to the observed value ‘? = Coefficient of determination .
than
1
F value would be greater
r 2a
0.60
than
where Y,dj and Y”nadj are adjusted and unadjusted group means, b = pooled within-class regression coefficient between each individual or subject’s experimental (unadjusted) and traiging (covariate) values for all the subjects, and X and X are training or covariate group and grand (for all groups) means respectively. The adjusted group means are presented in Table 4 and the percentage increases or decreases in performance are presented in Table 5. Figure 4, drawn with the adjusted means, shows the production output of the groups by day. The trends in performance of each group can be visualized from this figure. The adjusted means were used for the subsequent SNK range test for comparative analysis of the groups. The results of the SNK range test are presented in Table 6. Normal
production
standard
A comparison between Group 2 (100% normal and feedback) and Group 1 (control: no standard and no
A field study of worker productivity improvements Table 4 Adjusted group means of performance
(%)
feedback) showed that the assignment of a normal production standard with feedback of results improved the operator’s performance output significantly (p C 0.01). The increase in production output was about 12% compared with the control group. The result was not consistent with the laboratory study, where no significant difference was found between these conditions. The provision of a normal production standard along with feedback in real industry jobs was superior to no standard and no feedback or a simple ‘do your best’ standard.
Group
:Control)
13.63
2 (PS: 100% + PF)
3 (PS: 140% + PF
4 (PS: Partic. + PF)
5 (PS: 140% + MI)
6 (PS: Partic. + PF+MI)
82.82
90.18
107.38
103.43
116.25
increase or decrease in performance
Table 5 Percentage
Comparison 2 3 3 4 4 5 5 6 6 6
% increase in performance
between groups
(Assigned normal) vs 1 (Control) (Assigned hard) vs 1 vs2 (Participative) vs 1 vs 3 (Assigned hard + MI) vs 1 vs 3 (Participative + MI) vs 1 vs 4 vs 5
Assigned
hard production
140
Participative
x Gr. 1 (Conuol)
q
Gr. 2 (PS: Gr. 3 (l’s: Gr. 4 (PS: Gr. 5 (PS:
’
Gr. 6 (PS: Pticip.+PF+MI)
1
Figure
2
4 Production
3
4.
output
Groups 1 2 3 5 4 6
6
of groups
Table 6 Student Newman-Kuel’s Groups/differences
5
lOO%+PF) 140%+PF) Particip.+PF) .140%+PF+M9
7
8
9
10
by days
(SNK) range test for worker production
in adjusted
1 (Control)
2 (PS: MO% + PF)
-
9.19** -
production
standard
The subjects of the participative groups set themselves a standard of about 120% of normal on the average. A compqison between Group 4 (participative and feedback) and Group 1 (Control) revealed that the provision of a participative standard with feedback significantly improved worker performance. The increase in production output was about 46% compared with the control group. A comparison between Groups 4 and 3 (assigned hard) showed that the production output of the participative standard group was superior to that of the assigned hard standard group. Stated otherwise, the provision of a participative standard with feedback led to better performance than did an assigned hard standard of 140% of normal with feedback. The difference was about 19% in production output. The result was contrary to the laboratory study, in which the assigned hard standard of 140% of normal with feedback was significantly better in terms of production output than the participative standard with
80
A *
standard
A comparison between Group 3 (assigned 140% of normal and feedback) and Group 1 (Control) showed that the provision of an assigned hard standard and feedback had a highly significant positive effect on worker performance. The increase in production output was about 22% compared with the control group. The production output of Group 3 was significantly better than the production output of Group 2 (assigned normal). The increase was about 9%. This result was consistent with the result of the laboratory study. All the subjects accepted the hard standard. Probably, they found the job challenging and were motivated by the specific hard standard and feedback. From this it could be stated that a hard standard and feedback can improve worker productivity significantly compared to the normal standard and feedback.
12.48 22.48 8.89 45.83 19.07 40.47 14.69 51.88 8.26 12.39
l
25
output data
means between group@ --)
;PS: 140% + PF)
&:
140% + PF + MI
16.55** 7.36* -
29.80** 20.61** 13.25** -
aGroups in order of increasing differences in adjusted means (production *p < 0.05 (significant), **p < 0.01 (highly significant) Note: Adjusted production output for Group 1 (Control) = 73.63%
4 (PS: Participat. 33.75** 24.56’* 17.20** 3.95 -
output,
% of normal)
+ PF)
6 (PS: Part. + PF + MI) 42.62** 33.43** 26.07** 12.82** 8.87* -
26
A.A.
Shikdar and B. Das
feedback. Although the participative standard was set at a much lower level (on average) than the assigned hard standard, the worker production output was much higher. This indicates that in real settings a participative standard is preferred and people work harder to reach their own standard. Monetary
incentive
Monetary incentive was provided to the assigned hard (140% of normal) group (Group 5) and a participative standard with feedback group (Group 6) to determine whether monetary incentive would improve worker performance further. A comparison between Group 5 (140% of normal + feedback + monetary incentive) and Group 3 (140% of normal + feedback) revealed that the provision of monetary incentive along with the assigned hard standard and feedback further improved worker performance significantly. The improvement in production output for Group 5 was about 15% greater than Group 3 (Table 5). A comparison between Group 6 (participative + feedback + monetary incentive) and Group 4 (participative + feedback) showed that the provision of monetary incentive along with the participative standard and feedback resulted in significantly higher performance than the provision of participative standard with feedback only. The increase in production output for Group 6 was about 8% compared with Group 4. Stated otherwise, the provision of monetary incentive had a significant positive effect on worker performance. Compared with the control group, the improvements were about 58% for the participative standard with feedback and monetary incentive (Group 6) and 40% for the assigned hard standard (140%) with feedback and monetary incentive (Group 5). Monetary incentive did not have any effect when provided with an assigned hard standard (140%) and feedback in the laboratory studies conducted earlier. Discussion This study was conducted in a large fish-processing plant with a trimming task, as opposed to the drill-press operation in the previous laboratory study. Although the tasks were different, the methodology of these experiments remained very similar. It is evident that the results of the industrial study are different from the laboratory study in many aspects. Laboratory research has some inherent limitations, especially when human subjects are involved. The population sample and the work situation were not representative of the real-life work situation. In the present industrial study, the subjects were industrial workers, who worked in a real-life work situation and engaged in a normal 8 h work shift. However, the problems of conducting research in a real-life task situation should be recognized. Generally, industries are not interested in research or experimentation and would rather use strategy that others have previously found beneficial. Also, workers generally do not like to be studied. These problems were resolved by convincing both the union and management, through meetings and seminars, that the study would be beneficial to both parties and that any positive findings could be applied in the future to improve worker productivity in repetitive production tasks. It was clearly explained that the study
would be conducted without much disruption in usual production activities. An assigned normal production standard (100%) with feedback did not show any effect in the laboratory situation in terms of production output, but its effect was significant in the industrial situation. The specific normal standard with feedback was considered a substantial change in the work situation, sufficient to cause an improvement in worker performance. An assigned hard standard of 140% of normal, with feedback, was found to be the optimum standard condition in terms of production output in the laboratory settings. In the field study the improvement in production output was also significant compared with assigned normal standard with feedback, but this was not the optimum standard condition in industry. In the laboratory situation, the subjects who were assigned hard standards (140%) outperformed the subjects who had set their own standards. This result was reversed in industry. The performance of the participative standard with feedback condition was significantly better than the performance with the assigned hard standard of 140% and feedback. The operators probably perceived the assigned hard standard to be difficult and did not work harder, as there was no monetary gain. However, when the subjects set their own standards, they tried to reach the standard even though they had set relatively hard standards. The provision of a participative standard not only motivated them to work harder, but also reduced the pressure to reach a high standard. The difference in populations, student subjects in the laboratory versus industrial workers in the field, was probably mainly responsible for such outcomes. Monetary incentive in the laboratory situation did not have any effect on performance. It was speculated that as the scope to earn a substantial amount of money for the short time was limited (for student subjects) there was no further improvement due to monetary incentive. In industry, however, a monetary incentive had a significant effect on performance. In real life the workers have to make a living to maintain their quality of life. The results of this field study will have significant implications for industries where industrial managers are concerned with worker productivity improvement in repetitive tasks. There was no complaint of any adverse health effects from operators who had worked at a faster pace in assigned hard and participative standards conditions, although it was beyond the scope of the present research actually to measure the health effects. Conclusions On the basis of the results obtained in this particular industrial setting, the following conclusions are drawn.
(1) The (2)
provision of an assigned normal production standard (100% normal) with feedback improves worker productivity significantly. An assigned hard standard of 140% of normal with feedback of results, and a participative standard with feedback, improved worker productivity in industry significantly, compared with the provision
A field study of worker productivity improvements
of an assigned norm.al standard with feedback. A participative standard with feedback was, furthermore, superior to the assigned hard standard with feedback in terms of worker productivity. incentive along with (a) an assigned (3) Monetary hard standard and feedback of results and (b) a participative standard with feedback, further improved worker productivity. The participative standard with feedback and monetary incentive proved to be the best standard condition in industry. The improvement in performance was about 58% compared with the control condition. standards, performance feedback and (4) Production monetary incentives proved to be important job factors, as they significantly affected task performance. Participation of workers in setting standards should be considered an important factor in industry, especially in a unionized environment. (5) For maximum worker productivity improvements, a participative standard with feedback and a monetary incentive could be employed in industry for a repetitive production task under ergonomically designed working conditions. This may have the effect of somewhat increasing challenge and interest. Monetary incentives could be a viable approach for a continued employee commitment. To implement the positive outcomes of this research, the following future rese.arch is recommended. (1) The results of the study, and specifically the best standard condition., should be applied on a continuous basis for a longer period to investigate whether the effects would be sustained. (2) The possibility of adverse effects on health, especially cumulative trauma disorders (work-related upper limb disorders) as a result of working at a faster pace for a long time, needs to be investigated. attitudes and satisfaction under these (3) Worker circumstances need to be assessed.
Acknowledgements The authors would like to thank the management and employees of the ‘High Liner’ National Sea Products Ltd, Canada, for their facilities and participation, and the SSH Research Council of Canada for funding the research.
27
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Ammons,
14( 1), 27-37 Das, B. and Grady,
R.M. 1983 ‘Industrial workplace layout design: an application of engineering anthropometry’ Ergonomics 26(5),
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Locke, E.A. 1968 ‘Toward a theory of task motivation and incentives’ Organ Behav Hum Perform 3, 157-189 Locke, E.A. and Latham, G.P. 1984 Goal Setting: A motivational technique that works! Prentice-Hall Inc., NJ Locke, E.A., Shaw, K.N., Saari, L.M. and Latham, G.P. 1981 ‘Goal setting and task performance: 1968-1980’ Psycho1 Bull 90(l), 125-
152 Sanders, M.S. and McCormick, E.J. 1988 Human Factors in Engineering and Design 5th edn, McGraw-Hill, New York Ray, A.A. (ed.) 1982 SAS User Guide: Statistics SAS Institute Inc.,
Carry, NC A.A. 1991 ‘An investigation on the application of production standards, production feedback and monetary incentive in industry’, PhD Thesis, Department of Industrial Engineering, Technical University of Nova Scotia, Canada Shikdar, A.A. and Das, B. 1992 ‘The effects of assigning progressively harder production standards with feedback on worker productivity and satisfaction’ Znt .I Hum Factors Manuf 2(4), 325Shikdar,
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