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Typographic coding in lists and bibliographies
Applied Ergonomics 19 74, 5.3, 136-141
Typographic coding in lists and bibliographies H. Spencer, Linda Reynolds and B. Coe Readability of Print Research Unit, Royal College of Art, London
A comparison was made of the effectiveness of ten systems of typographical/spatial coding suitable for use in the presentation of highly structured information such as bibliographic material. With one exception, which requires a bold typeface, the systems tested are all suitable for the preparation of copy on a standard typewriter or an upper and lowercase line printer. Sections of alphabetical author index were typed in each of the ten styles and subjects were asked to look up lists of entries in each style. The most effective system on balance was a two-unit left extension of the first line of each entry.
This study is concerned with certain specific aspects of the presentation of highly structured information in print. The speed with which information can be extracted from material which has an inherent logical structure depends on the way in which this structure is indicated on the page. This is particularly true of material which is made up of essentially similar units arranged in some specified order to form a list. The speed with which the user is able to appreciate this structure and to use his understanding of it in searching for specific items of information depends on the way in which the units within the structure are distinguished from one another on the page. This distinction is usually achieved by means of a coding system of some kind, either spatial, typographic, or some combination of both. Spatial coding includes devices such as line spacing and indentation, while typographic coding implies the use of symbols of a different design, such as capitals, italics or bold, or the use of additional symbols such as parentheses. The relative effectiveness of these various coding devices depends on the nature of the information and on the way in which it is intended to be used. Coding systems differ not only in their effectiveness but also in their practical implications in terms of the level of sophistication of composition equipment required, speed of setting, and paper and binding costs. Some quantitative measure of the relative effectiveness of alternative coding systems is therefore needed so that the advantages in terms of effectiveness of using one system rather than another may be weighed against any differences in terms of costs. Bibliographic material is an example of highly structured information which is made up of similar units, or entries, listed in a specified order. The use of such material often involves searching for a particular entry or entries - for example, in author and title indexes. The user's first problem in searching such indexes is to
136
AppliedErgonomics September 1974
distinguish the entries as discrete entities. The ease with which he is able to do this depends on how dearly the beginning of each entry is demarcated from the end of the preceding entry. Having located the beginning of an entry his second task is to identify the entry by examining some feature of it, usually the first word. In searching for a specific entry the user will usually systematically narrow his search area within the index by sampling entries at intervals. In effect he builds up a model of the structure and scale of the index, and the speed with which he is able to do this depends on how easily he can distinguish and identify entries. Methods of coding the start of an entry and/or of drawing attention to the first word of the entry are compared here; the third problem, that of locating specific information within a structured entry, will be considered in a later study. The relative effectiveness of coding systems suitable for bibliographic material is of considerable significance because such material is in many instances produced on a low budget and against a deadline, and copy is typically typewritten or in the form of line printer output. Given these limitations it is especially important that attention should be paid to the layout/typography of the material to achieve maximum ease of use at minimum cost. The coding systems tested in this study are all suitable for use on relatively unsophisticated composition equipment such as is typically used for the production of bibliographic material.
Coding systems T he ten coding systems selected for study were limited to variations in layout and typography within a single column format. In all ten systems each entry began a new line, and nine of the systems were in upper and lowercase. Fig 1 illustrates the systems tested; they can be classified by the type of coding and the distinctions made, as shown in Table 1.
I
System I
PAGE, MIC}IAEI, FITZGERALD. FOR~INES OF WAR. HAL£. £1.90. 823.91F (B72-I0444) ISBN 0 7091 2803 7 PALLAS, NORVIN. CODE GAr,~S. STERLfNG; DIS'L'I~IBUTED BY WARD LOCK. £i.05. 001.5436 (B72-09950) I S ~ 0 7061 2328 x
System 2
Allman, Michael. Geological laboratory techniques. Blanford Press. g8.50. 550.28 (B72-17338) ISBN 0 7137 O559 0 Allsop, Kenneth. Adventure lit their star. Revised ed. Penguin. £0.35. 823.91F (B72-17562) ISBN 0 14 003446 3
System 3
HAIGH, Basil. Organic chemistry of nucleic acids. Part A. Plenum Press. £9.00. 547.596 (B72-10819) ISBN 0 306 37531 1 HAINING, Peter. The Channel Islands. Revised ed. New English Library. £1.50. 914.2340485 (B72-12211)
System 4
~rrett, Edward Joseph. Essentials of organic chemistry. Holt, Rinehart and Winston. £5.00. 547 (B72-17335) ISBN 0 03 080348 9 Barrow, Charles Clement. A short history of the S.
System 5
Bartlett, Kathleen. Lovers in Autumn. Hale. £1.30. 823.91F (B72-10379) ISBN 0 7091 2329 9 Bassett, Michael Gwyn. Catalogue of type, figured & cited fossils in the National Museum of Wales. National Museum
System 6
-Cartland, Barbara. A ghost in Monte Carlo. Arrow Books Ltd. £0.25. 823.9]2 (B72-12081) ISBN 0 09 906180 5 -Cartwright, Frederick Fox. Disease and history. Hart-Davis. £2.50. 904.5 (B72-11136) ISBN 0 246 10537 2
System 7
Edson, John Thomas. Wagons to Backsight. Hale. £i.i0. 823.91F (B72-10401) ISBN 07091 2394 9 Efemey, Raymond. The story of the parish church of St Thomas, Dudley. 5th ed. British Publishing. Unpriced.
System 8
System 9
System I0
Cadell, Elizabeth. Bridal array. White Lion Publishers Ltd. £1.80. 823.91F (B72-17578) ISBN 0 85617 622 2 Cafferty, Bernard. Spassky's 100 best games. Batsford. £2.50. 794.159 (B72-16145) ISBN 0 7134 0362 4
Manessier, Alfred. Manessier. Adams and Dart. £10.50. 759.4 (B72-10983) ISBN 0 239 00098 6 Mangalam, J J. Mountain families in transition: a case study of Appalachian migration. Pennsylvania State
FARNHAM, Ann. Action mathematics. 5. Cassell. £0.65. (non-net) 372.73045 (B72-15925) ISBN 0 304 93803 3 FARQUHAR, Ronald M. The earth's age and geochronology. Pergamon. £2.50. 551.701 (B72-17343) ISBN 0 08 016387 4
Fig 1 The coding systemstested Applied Ergonomics September 1974
137
Table 1: Classification of the ten coding systems No distinctions No distinctions
Entry distinguished
First word distinguished
Entry and first word distinguished
1. Entries in capitals throughout 2 Entries in upper and lower case
Spatial distinction
7 Two unit left extension of first line of each entry 8 Half line space between entries 9 Two unit left extension of first line and half line space between entries
Typographic distinction
6 Single unit dash 3 Firstword in capitals in margin 4 First word in bold 5 First word underlined
Spatial and typographic distinctions
10 First word in capitals and half line space between entries
In practical terms, System 1 is the simplest because it requires the smallest character set; System 2 requires upper and lowercase, as do all the other systems. Systems 3, 6, 7 and 8 require no additional type dimension, but System 4 does require an extra font. System 5 will necessitate backspacing on most typewriters and is therefore likely to increase composition time. Systems 8, 9 and 10, because they include a half line space between entries, are likely to increase paper and binding costs. Experimental design Test material Author indexes from British National Bibliography weekly lists were used as a source of test material. Certain types of entry were eliminated from the lists so that each surname occured once only and remaining entries were of similar length and content. Two sections of index from two different letters of the alphabet were assigned to each coding system so that the relative effectiveness of each system would not be determined on the basis of surnames beginning with any one letter. A further section of index was prepared for use as an initial test to ensure that subjects had understood their instructions. The selected sections were typed, using the appropriate coding systems, on an electric typewriter. Each section comprised, in its Final form, two A4 pages carrying a total of between 36 and 42 typed entries. The material was printed by the offset litho process and made up into two-page booklets, each with a front cover. The booklets were then grouped into 90 sets of 21, each set comprising two index sections for each coding system and one initial test section. 138
Applied Ergonomics
September 1974
Selection of questions Each booklet also contained a question sheet comprising a randomly ordered list of 12 authors' surnames selected from those in the booklet. No less than five of the names could occur on either one of the two pages. To ensure that any differences between the booklets in terms of subjects' scores could not be solely attributable to differences in the difficulty of the question sheets, three different lists of names were selected for each booklet. No name could appear on more than one list so that a total of 36 entries was sampled over the three question sheets for each booklet. The question sheets were used in three sets, designated (a), (b) and (c). The 90 sets of test material were numbered I - 90 and the same question set was assigned to every third set of booklets. Order of presentation of test material The booklets in each set were presented in different but strictly controlled orders designed to balance practice effects and carry-over effects. The initial test booklet was always shown first and the two booklets for each coding system were always shown consecutively, but the t e n coding systems were presented in 90 different orders derived from 9 similar 10 x 10 latin squares. Subjects Male and female students from five higher education establishments were subjects. The sources, disciplines and numbers of subjects are given in Table 2. For practical reasons, it was not possible to allocate test material in any logical fashion to subjec, s from each of the five sources, and
Table 2: Characteristics of subject source Source
Discipline
Number of subjects
Mean score
Standard deviation
A
Librarianship
25
6"61
2"00
B
Information science
17
7"17
1"74
C
Technology
31
4"69
1"76
19
Industrial design
13
5"06
1"76
E
Science
4
6"46
1"64
Table 3: Incidence of errors Errors
Type 1 Omissions
Type 2 Similar name Type 3 Next entry down Type 4 Entry above Total
Coding systems 1
2
3
4
5
6
7
8
9
10
8
9
4
5
7
11
7
5
4
3
63
11
5
7
5
5
4
4
-
3
17
61
1
4
2
5
-
1
2
17
1
-
-
-
-
-
-
2
21
18
13
15
5
8
22
13
17
11
no attempt was made to balance the numbers or control the distribution of male and female subjects over the 90 sets of test material.
Test procedure Subjects were each given a set of test material and were asked to work through the booklets in the order given. For each booklet they were allowed 45 s in which to find as many as possible of the 12 names listed on the corresponding question sheet, taking the names in the orderlisted and underlining the price of the book in the appropriate entry in the booklet. After the initial test booklet, subjects' answers were checked to ensure that they had understood the instructions. They then proceeded to the experimental booklets. Subjects were asked to underline the price of the book rather than the author's name because this was thought to provide a more severe test of distinctions between entries. Having located the correct entry, subjects had to make certain that the price they underlined was associated with that entry, and not with the one above or the one below. The liklihood of underlining material in an adjacent entry by mistake would depend on how clearly the entries were distinguished from one another. Results
Analysis of results Subjects scored 1 for each price correctly underlined, giving a maximum score of 12 on each booklet. If more than two consecutive questions on a sheet were omitted, the subject's results were discounted and the set of booklets retested. All errors were recorded and classified.
Total
143
Analysis of errors Errors were classified as one of five types: Type 1. Subjects omitted questions, presumably because they were unable to locate the entry in the booklet. Type 2. Subjects underlined the price in an entry with a name similar to, but not the same as, that given on the question sheet. For example, names such as Webber and Weber, Cassell and Cassells, Tomkins and Tompkin, Patten and Patton, were confused. Type 3. Subjects underlined the price in the entry immediately below that given on the question sheet. Type 4. Subjects underlined the price in the entry immediately above that given on the question sheet. Type 5. Subjects underlined some part of the entry other than the price, usually the first word. The occurrences of the four main types of error are given in Table 3. The incidence of errors of each type might be expected to be related to the characteristics of the coding systems on which they occurred. One might, for example, expect less Type 2 errors on coding systems where the authors' names were clearly distinguished and thus easily comparable with one another, and where the names were in upper and lowercase so that their shapes could be directly compared with those on the upper and lowercase question sheets. Type 2 errors were indeed highest on Systems 10, 1 and 3, all of which had the authors' names in capitals. Certain questions on Systems I and 10 did, however, provide a Applied Ergonomics
September 1974
139
High scoring subject group I 6 2
53
II
I
4 1089
II
7
IIII
I
I
I
I
I
I
I
I
I
I
t
0
I0
20
30
40
50
60
70
80
90
I
II
I2
II
6
Low scoring subject group All subjects I
II
I
0
I0
TI
20
I
s3
I
I
30
40
III
8
35
,I
I
50
60
I
100%
I
Io.9
7
IO 84 9
7
.I
70
ill
I
l
80
90
i
I
ICO°/o
Fig 2. Relative effectiveness of coding systems 1 - 10: differences between mean scores are plotted on a percentage scale, taking the difference between systems 7 and 1 as a difference of 100%. The following system groups do not differ significantly from one another: 1, 2 and 6; 6, 3 and 5; 3, 5, 8, 10 and 4; 8, 10, 4, 9 and 7.
particularly severe test, and the majority of Type 2 errors could probably be attributed to subjects marking the first name they encountered which would be pronounced in a similar way to that given on the question sheet. The incidence of such errors seemed to be more closely related to the occurrence of pairs of similar names rather than to the characteristics of any particular coding systems. Errors of Types 3 and 4 might be expected to have been less on systems which made a clear spatial distinction between entries. There were 17 Type 3 errors, 14 of which occurred on Systems 1,2, 3, 4 or 6. None of these systems made any spatial distinction between entries. Ten of the 14 errors occurred where the last line of the correct entry was full, two occurred where the publication was described as 'Free' or 'Unpriced' (presumably causing subjects to search on for a numerical price), and two occurred on a question where both of these conditions held. The remaining three errors were on Systems 9 and 10 and could not be attributed to any specific cause.
Analysis of scores
Breakdown of source of subjects Examination of subjects' individual mean scores revealed differences in the performance of subjects from the five sources. The mean scores for subjects from each source are given in Table 2. It may be significant that subjects from the sources with the highest mean scores, sources A, B and E, were familiar with bibliographic materials whereas subjects from sources C and D were almost certainly much less so.
Breakdown by question sets The mean scores for the three question sets, (a), (b) and (c) were 5.87 + 1-98, 5.73 -+ 2-15 and 5-8 +- 2-15 respectively. The similarity of these figures suggests that the three question sets were of equal difficulty overall. In general, the mean scores on the three question sheets for any given booklet were fairly close. Marked differences were mostly attributable to some specific cause such as confusion between pairs of similar names.
Breakdown by index sections The mean scores on the two booklets representing each coding system were very similar in most Cases. Large 140
Applied Ergonomics
September 1974
differences between pairs of booklets were usually either the result of difficulties over specific entries and questions, or they were the result of characteristics of authors' names beginning with a particular letter of the alphabet. For example, all entries in index section 6C began with 'Ca' so that subjects had to search further into each name to identify it, whereas names in 6S ranged from 'Sa' to 'Sh'. Similarly, section 9M had a relatively high proportion of foreign names.
Breakdown by coding systems The mean scores for the ten coding systems are given in Table 4. The apparent significance of the differences between these means was confirmed by a one-way analysis of variance (p < 0-01), indicating that the coding systems were indeed influencing subjects' performance. Subsequent comparison of pairs of means using Scheffe's method indicated significant differences between coding systems as shown in Table 4. The relative sizes of the differences between the systems are illustrated in Fig 2, which shows the percentage differences between the coding systems, taking the difference between the means for the best and worse systems as a difference of 100%. Systems grouped within brackets do not differ significantly from one another.
Practice effects Comparison of the mean scores for the ten presentation positions of the coding systems, taken over 90 subjects, showed that subjects' performance improved over the ftrst four systems (eight booklets) seen, but after this there was no further marked improvement. Since each system occurred an equal number of times in each position, these effects were balanced and did not influence the ranking of the coding systems. Discussion of results
The coding systems with the highest mean scores were Systems 7 and 9, as shown in Table 4 and Fig 2. The twounit left extension of the first line in these two systems apparently distinguished very effectively between successive entries, and caused the authors' names to stand out so that Table 4: Relative effectiveness of coding systems 1--10 Rank
Coding system
Mean Significantly score inferior systems
Significance levels
1
7
7"05
5,3,6,2,1
p
2
9
6"59
5,3 6,2,1
p
3
10
6"44
6,2,1
p
4
4
6"43
6,2,1
p
5
8
6"35
6,2,1
p
6
5
5-69
2,1
p
7
3
5-68
2,1
p
8
6
4-93
9
2
4"69
10
1
4"40
they could easily be compared with one another. Possibly the additional half line space between entries in System 9 made this comparison of names slightly more difficult, though the difference between the two systems was not significant. The small difference between Systems 4 and 10, both of which distinguish the name of the author from the rest of the entry, suggests that the half line space between entries in System 10 did not provide any advantage. It may be, however, that the upper and lowercase bold names in System 4 were so much more helpful than the capitals in System 10 that the effects of the spatial coding were masked. Similarly, System 8, with a half line space between entries but no distinction of the authors' names, was not significantly better than System 4, again suggesting that the additional space provided no advantage over the strong typographic distinction of authors' names in System 4. The fact that System 8 was not significantly less effective than System 10 with the authors in capitals again suggests that the capitals were not especially helpful. The mean scores for Systems 5 and 3 suggest that the use of capitals and of underlining upper and lowercase were similarly effective. The distinction between entries made by the unit dash in System 6 was seemingly not especially helpful since scores were not significantly better than those on Systems 1 and 2.
Conclusions The results of this study suggest that the most effective coding systems for highly structured information such as bibliographic material are those which make a clear distinction between successive entries and between the first word of each entry and the rest of the entry. The four most effective systems tested, Systems 7, 9, 10 and 4, all in effect make both of these distinctions. System 8, distinguishing between entries only, but strongly, was not significantly less effective. Systems 3 and 5, distinguishing the first word from the rest of the entry, were slightly less
effective than System 4, which makes such a strong distinction of the first word that it possibly helped to distinguish between the entries. System 6, with its weak distinction between entries, was little more effective than Systems 1 and 2 which make no distinctions at all and were the least effective. Considering the relative effectiveness of the coding systems in relation to their practical implications, System 7 is not only the most effective system, it is also one of the most practical since it is economical in terms of space and it requires no extra type dimension. There is no advantage in using System 9 in terms of effectiveness and this system uses more space than System 7. There is little to choose between Systems 10, 8 and 4. Systems 10 and 8, both having a half line space between entries, require more space than System 7; System 4, although it uses no more space, does require the use of bold type. Systems 3 and 5 are both economical in terms of space and require no extra type dimension (though System 5 does necessitate underlining), but under normal circumstances there would be no advantage in using them in preference to System 7 which was significantly more effective. Systems 1,2 and 6 were relatively so ineffective that they are not worth considering when there are better systems which could be used at no extra cost. It would seem therefore that it is possible to produce bibliographical material on a standard typewriter or on an upper and lowercase line printer in such a way as to optimise the ease of use of the material without any significant increase in cost in terms of equipment, paper and binding costs, or time. Even where computer printout is restricted to uppercase only, a spatial coding system such as System 7 could still be used to great advantage.
Acknowledgement This study was conducted as part of a programme of research into the readability of print in information publishing, supported by a grant from the Office for Scientific and Technical Information.
Applied Ergonomics September 1974
141
Typographic coding in lists and bibliographies H. Spencer, Linda Reynolds and B. Coe Readability of Print Research Unit, Royal College of Art, London
A comparison was made of the effectiveness of ten systems of typographical/spatial coding suitable for use in the presentation of highly structured information such as bibliographic material. With one exception, which requires a bold typeface, the systems tested are all suitable for the preparation of copy on a standard typewriter or an upper and lowercase line printer. Sections of alphabetical author index were typed in each of the ten styles and subjects were asked to look up lists of entries in each style. The most effective system on balance was a two-unit left extension of the first line of each entry.
This study is concerned with certain specific aspects of the presentation of highly structured information in print. The speed with which information can be extracted from material which has an inherent logical structure depends on the way in which this structure is indicated on the page. This is particularly true of material which is made up of essentially similar units arranged in some specified order to form a list. The speed with which the user is able to appreciate this structure and to use his understanding of it in searching for specific items of information depends on the way in which the units within the structure are distinguished from one another on the page. This distinction is usually achieved by means of a coding system of some kind, either spatial, typographic, or some combination of both. Spatial coding includes devices such as line spacing and indentation, while typographic coding implies the use of symbols of a different design, such as capitals, italics or bold, or the use of additional symbols such as parentheses. The relative effectiveness of these various coding devices depends on the nature of the information and on the way in which it is intended to be used. Coding systems differ not only in their effectiveness but also in their practical implications in terms of the level of sophistication of composition equipment required, speed of setting, and paper and binding costs. Some quantitative measure of the relative effectiveness of alternative coding systems is therefore needed so that the advantages in terms of effectiveness of using one system rather than another may be weighed against any differences in terms of costs. Bibliographic material is an example of highly structured information which is made up of similar units, or entries, listed in a specified order. The use of such material often involves searching for a particular entry or entries - for example, in author and title indexes. The user's first problem in searching such indexes is to
136
AppliedErgonomics September 1974
distinguish the entries as discrete entities. The ease with which he is able to do this depends on how dearly the beginning of each entry is demarcated from the end of the preceding entry. Having located the beginning of an entry his second task is to identify the entry by examining some feature of it, usually the first word. In searching for a specific entry the user will usually systematically narrow his search area within the index by sampling entries at intervals. In effect he builds up a model of the structure and scale of the index, and the speed with which he is able to do this depends on how easily he can distinguish and identify entries. Methods of coding the start of an entry and/or of drawing attention to the first word of the entry are compared here; the third problem, that of locating specific information within a structured entry, will be considered in a later study. The relative effectiveness of coding systems suitable for bibliographic material is of considerable significance because such material is in many instances produced on a low budget and against a deadline, and copy is typically typewritten or in the form of line printer output. Given these limitations it is especially important that attention should be paid to the layout/typography of the material to achieve maximum ease of use at minimum cost. The coding systems tested in this study are all suitable for use on relatively unsophisticated composition equipment such as is typically used for the production of bibliographic material.
Coding systems T he ten coding systems selected for study were limited to variations in layout and typography within a single column format. In all ten systems each entry began a new line, and nine of the systems were in upper and lowercase. Fig 1 illustrates the systems tested; they can be classified by the type of coding and the distinctions made, as shown in Table 1.
I
System I
PAGE, MIC}IAEI, FITZGERALD. FOR~INES OF WAR. HAL£. £1.90. 823.91F (B72-I0444) ISBN 0 7091 2803 7 PALLAS, NORVIN. CODE GAr,~S. STERLfNG; DIS'L'I~IBUTED BY WARD LOCK. £i.05. 001.5436 (B72-09950) I S ~ 0 7061 2328 x
System 2
Allman, Michael. Geological laboratory techniques. Blanford Press. g8.50. 550.28 (B72-17338) ISBN 0 7137 O559 0 Allsop, Kenneth. Adventure lit their star. Revised ed. Penguin. £0.35. 823.91F (B72-17562) ISBN 0 14 003446 3
System 3
HAIGH, Basil. Organic chemistry of nucleic acids. Part A. Plenum Press. £9.00. 547.596 (B72-10819) ISBN 0 306 37531 1 HAINING, Peter. The Channel Islands. Revised ed. New English Library. £1.50. 914.2340485 (B72-12211)
System 4
~rrett, Edward Joseph. Essentials of organic chemistry. Holt, Rinehart and Winston. £5.00. 547 (B72-17335) ISBN 0 03 080348 9 Barrow, Charles Clement. A short history of the S.
System 5
Bartlett, Kathleen. Lovers in Autumn. Hale. £1.30. 823.91F (B72-10379) ISBN 0 7091 2329 9 Bassett, Michael Gwyn. Catalogue of type, figured & cited fossils in the National Museum of Wales. National Museum
System 6
-Cartland, Barbara. A ghost in Monte Carlo. Arrow Books Ltd. £0.25. 823.9]2 (B72-12081) ISBN 0 09 906180 5 -Cartwright, Frederick Fox. Disease and history. Hart-Davis. £2.50. 904.5 (B72-11136) ISBN 0 246 10537 2
System 7
Edson, John Thomas. Wagons to Backsight. Hale. £i.i0. 823.91F (B72-10401) ISBN 07091 2394 9 Efemey, Raymond. The story of the parish church of St Thomas, Dudley. 5th ed. British Publishing. Unpriced.
System 8
System 9
System I0
Cadell, Elizabeth. Bridal array. White Lion Publishers Ltd. £1.80. 823.91F (B72-17578) ISBN 0 85617 622 2 Cafferty, Bernard. Spassky's 100 best games. Batsford. £2.50. 794.159 (B72-16145) ISBN 0 7134 0362 4
Manessier, Alfred. Manessier. Adams and Dart. £10.50. 759.4 (B72-10983) ISBN 0 239 00098 6 Mangalam, J J. Mountain families in transition: a case study of Appalachian migration. Pennsylvania State
FARNHAM, Ann. Action mathematics. 5. Cassell. £0.65. (non-net) 372.73045 (B72-15925) ISBN 0 304 93803 3 FARQUHAR, Ronald M. The earth's age and geochronology. Pergamon. £2.50. 551.701 (B72-17343) ISBN 0 08 016387 4
Fig 1 The coding systemstested Applied Ergonomics September 1974
137
Table 1: Classification of the ten coding systems No distinctions No distinctions
Entry distinguished
First word distinguished
Entry and first word distinguished
1. Entries in capitals throughout 2 Entries in upper and lower case
Spatial distinction
7 Two unit left extension of first line of each entry 8 Half line space between entries 9 Two unit left extension of first line and half line space between entries
Typographic distinction
6 Single unit dash 3 Firstword in capitals in margin 4 First word in bold 5 First word underlined
Spatial and typographic distinctions
10 First word in capitals and half line space between entries
In practical terms, System 1 is the simplest because it requires the smallest character set; System 2 requires upper and lowercase, as do all the other systems. Systems 3, 6, 7 and 8 require no additional type dimension, but System 4 does require an extra font. System 5 will necessitate backspacing on most typewriters and is therefore likely to increase composition time. Systems 8, 9 and 10, because they include a half line space between entries, are likely to increase paper and binding costs. Experimental design Test material Author indexes from British National Bibliography weekly lists were used as a source of test material. Certain types of entry were eliminated from the lists so that each surname occured once only and remaining entries were of similar length and content. Two sections of index from two different letters of the alphabet were assigned to each coding system so that the relative effectiveness of each system would not be determined on the basis of surnames beginning with any one letter. A further section of index was prepared for use as an initial test to ensure that subjects had understood their instructions. The selected sections were typed, using the appropriate coding systems, on an electric typewriter. Each section comprised, in its Final form, two A4 pages carrying a total of between 36 and 42 typed entries. The material was printed by the offset litho process and made up into two-page booklets, each with a front cover. The booklets were then grouped into 90 sets of 21, each set comprising two index sections for each coding system and one initial test section. 138
Applied Ergonomics
September 1974
Selection of questions Each booklet also contained a question sheet comprising a randomly ordered list of 12 authors' surnames selected from those in the booklet. No less than five of the names could occur on either one of the two pages. To ensure that any differences between the booklets in terms of subjects' scores could not be solely attributable to differences in the difficulty of the question sheets, three different lists of names were selected for each booklet. No name could appear on more than one list so that a total of 36 entries was sampled over the three question sheets for each booklet. The question sheets were used in three sets, designated (a), (b) and (c). The 90 sets of test material were numbered I - 90 and the same question set was assigned to every third set of booklets. Order of presentation of test material The booklets in each set were presented in different but strictly controlled orders designed to balance practice effects and carry-over effects. The initial test booklet was always shown first and the two booklets for each coding system were always shown consecutively, but the t e n coding systems were presented in 90 different orders derived from 9 similar 10 x 10 latin squares. Subjects Male and female students from five higher education establishments were subjects. The sources, disciplines and numbers of subjects are given in Table 2. For practical reasons, it was not possible to allocate test material in any logical fashion to subjec, s from each of the five sources, and
Table 2: Characteristics of subject source Source
Discipline
Number of subjects
Mean score
Standard deviation
A
Librarianship
25
6"61
2"00
B
Information science
17
7"17
1"74
C
Technology
31
4"69
1"76
19
Industrial design
13
5"06
1"76
E
Science
4
6"46
1"64
Table 3: Incidence of errors Errors
Type 1 Omissions
Type 2 Similar name Type 3 Next entry down Type 4 Entry above Total
Coding systems 1
2
3
4
5
6
7
8
9
10
8
9
4
5
7
11
7
5
4
3
63
11
5
7
5
5
4
4
-
3
17
61
1
4
2
5
-
1
2
17
1
-
-
-
-
-
-
2
21
18
13
15
5
8
22
13
17
11
no attempt was made to balance the numbers or control the distribution of male and female subjects over the 90 sets of test material.
Test procedure Subjects were each given a set of test material and were asked to work through the booklets in the order given. For each booklet they were allowed 45 s in which to find as many as possible of the 12 names listed on the corresponding question sheet, taking the names in the orderlisted and underlining the price of the book in the appropriate entry in the booklet. After the initial test booklet, subjects' answers were checked to ensure that they had understood the instructions. They then proceeded to the experimental booklets. Subjects were asked to underline the price of the book rather than the author's name because this was thought to provide a more severe test of distinctions between entries. Having located the correct entry, subjects had to make certain that the price they underlined was associated with that entry, and not with the one above or the one below. The liklihood of underlining material in an adjacent entry by mistake would depend on how clearly the entries were distinguished from one another. Results
Analysis of results Subjects scored 1 for each price correctly underlined, giving a maximum score of 12 on each booklet. If more than two consecutive questions on a sheet were omitted, the subject's results were discounted and the set of booklets retested. All errors were recorded and classified.
Total
143
Analysis of errors Errors were classified as one of five types: Type 1. Subjects omitted questions, presumably because they were unable to locate the entry in the booklet. Type 2. Subjects underlined the price in an entry with a name similar to, but not the same as, that given on the question sheet. For example, names such as Webber and Weber, Cassell and Cassells, Tomkins and Tompkin, Patten and Patton, were confused. Type 3. Subjects underlined the price in the entry immediately below that given on the question sheet. Type 4. Subjects underlined the price in the entry immediately above that given on the question sheet. Type 5. Subjects underlined some part of the entry other than the price, usually the first word. The occurrences of the four main types of error are given in Table 3. The incidence of errors of each type might be expected to be related to the characteristics of the coding systems on which they occurred. One might, for example, expect less Type 2 errors on coding systems where the authors' names were clearly distinguished and thus easily comparable with one another, and where the names were in upper and lowercase so that their shapes could be directly compared with those on the upper and lowercase question sheets. Type 2 errors were indeed highest on Systems 10, 1 and 3, all of which had the authors' names in capitals. Certain questions on Systems I and 10 did, however, provide a Applied Ergonomics
September 1974
139
High scoring subject group I 6 2
53
II
I
4 1089
II
7
IIII
I
I
I
I
I
I
I
I
I
I
t
0
I0
20
30
40
50
60
70
80
90
I
II
I2
II
6
Low scoring subject group All subjects I
II
I
0
I0
TI
20
I
s3
I
I
30
40
III
8
35
,I
I
50
60
I
100%
I
Io.9
7
IO 84 9
7
.I
70
ill
I
l
80
90
i
I
ICO°/o
Fig 2. Relative effectiveness of coding systems 1 - 10: differences between mean scores are plotted on a percentage scale, taking the difference between systems 7 and 1 as a difference of 100%. The following system groups do not differ significantly from one another: 1, 2 and 6; 6, 3 and 5; 3, 5, 8, 10 and 4; 8, 10, 4, 9 and 7.
particularly severe test, and the majority of Type 2 errors could probably be attributed to subjects marking the first name they encountered which would be pronounced in a similar way to that given on the question sheet. The incidence of such errors seemed to be more closely related to the occurrence of pairs of similar names rather than to the characteristics of any particular coding systems. Errors of Types 3 and 4 might be expected to have been less on systems which made a clear spatial distinction between entries. There were 17 Type 3 errors, 14 of which occurred on Systems 1,2, 3, 4 or 6. None of these systems made any spatial distinction between entries. Ten of the 14 errors occurred where the last line of the correct entry was full, two occurred where the publication was described as 'Free' or 'Unpriced' (presumably causing subjects to search on for a numerical price), and two occurred on a question where both of these conditions held. The remaining three errors were on Systems 9 and 10 and could not be attributed to any specific cause.
Analysis of scores
Breakdown of source of subjects Examination of subjects' individual mean scores revealed differences in the performance of subjects from the five sources. The mean scores for subjects from each source are given in Table 2. It may be significant that subjects from the sources with the highest mean scores, sources A, B and E, were familiar with bibliographic materials whereas subjects from sources C and D were almost certainly much less so.
Breakdown by question sets The mean scores for the three question sets, (a), (b) and (c) were 5.87 + 1-98, 5.73 -+ 2-15 and 5-8 +- 2-15 respectively. The similarity of these figures suggests that the three question sets were of equal difficulty overall. In general, the mean scores on the three question sheets for any given booklet were fairly close. Marked differences were mostly attributable to some specific cause such as confusion between pairs of similar names.
Breakdown by index sections The mean scores on the two booklets representing each coding system were very similar in most Cases. Large 140
Applied Ergonomics
September 1974
differences between pairs of booklets were usually either the result of difficulties over specific entries and questions, or they were the result of characteristics of authors' names beginning with a particular letter of the alphabet. For example, all entries in index section 6C began with 'Ca' so that subjects had to search further into each name to identify it, whereas names in 6S ranged from 'Sa' to 'Sh'. Similarly, section 9M had a relatively high proportion of foreign names.
Breakdown by coding systems The mean scores for the ten coding systems are given in Table 4. The apparent significance of the differences between these means was confirmed by a one-way analysis of variance (p < 0-01), indicating that the coding systems were indeed influencing subjects' performance. Subsequent comparison of pairs of means using Scheffe's method indicated significant differences between coding systems as shown in Table 4. The relative sizes of the differences between the systems are illustrated in Fig 2, which shows the percentage differences between the coding systems, taking the difference between the means for the best and worse systems as a difference of 100%. Systems grouped within brackets do not differ significantly from one another.
Practice effects Comparison of the mean scores for the ten presentation positions of the coding systems, taken over 90 subjects, showed that subjects' performance improved over the ftrst four systems (eight booklets) seen, but after this there was no further marked improvement. Since each system occurred an equal number of times in each position, these effects were balanced and did not influence the ranking of the coding systems. Discussion of results
The coding systems with the highest mean scores were Systems 7 and 9, as shown in Table 4 and Fig 2. The twounit left extension of the first line in these two systems apparently distinguished very effectively between successive entries, and caused the authors' names to stand out so that Table 4: Relative effectiveness of coding systems 1--10 Rank
Coding system
Mean Significantly score inferior systems
Significance levels
1
7
7"05
5,3,6,2,1
p
2
9
6"59
5,3 6,2,1
p
3
10
6"44
6,2,1
p
4
4
6"43
6,2,1
p
5
8
6"35
6,2,1
p
6
5
5-69
2,1
p
7
3
5-68
2,1
p
8
6
4-93
9
2
4"69
10
1
4"40
they could easily be compared with one another. Possibly the additional half line space between entries in System 9 made this comparison of names slightly more difficult, though the difference between the two systems was not significant. The small difference between Systems 4 and 10, both of which distinguish the name of the author from the rest of the entry, suggests that the half line space between entries in System 10 did not provide any advantage. It may be, however, that the upper and lowercase bold names in System 4 were so much more helpful than the capitals in System 10 that the effects of the spatial coding were masked. Similarly, System 8, with a half line space between entries but no distinction of the authors' names, was not significantly better than System 4, again suggesting that the additional space provided no advantage over the strong typographic distinction of authors' names in System 4. The fact that System 8 was not significantly less effective than System 10 with the authors in capitals again suggests that the capitals were not especially helpful. The mean scores for Systems 5 and 3 suggest that the use of capitals and of underlining upper and lowercase were similarly effective. The distinction between entries made by the unit dash in System 6 was seemingly not especially helpful since scores were not significantly better than those on Systems 1 and 2.
Conclusions The results of this study suggest that the most effective coding systems for highly structured information such as bibliographic material are those which make a clear distinction between successive entries and between the first word of each entry and the rest of the entry. The four most effective systems tested, Systems 7, 9, 10 and 4, all in effect make both of these distinctions. System 8, distinguishing between entries only, but strongly, was not significantly less effective. Systems 3 and 5, distinguishing the first word from the rest of the entry, were slightly less
effective than System 4, which makes such a strong distinction of the first word that it possibly helped to distinguish between the entries. System 6, with its weak distinction between entries, was little more effective than Systems 1 and 2 which make no distinctions at all and were the least effective. Considering the relative effectiveness of the coding systems in relation to their practical implications, System 7 is not only the most effective system, it is also one of the most practical since it is economical in terms of space and it requires no extra type dimension. There is no advantage in using System 9 in terms of effectiveness and this system uses more space than System 7. There is little to choose between Systems 10, 8 and 4. Systems 10 and 8, both having a half line space between entries, require more space than System 7; System 4, although it uses no more space, does require the use of bold type. Systems 3 and 5 are both economical in terms of space and require no extra type dimension (though System 5 does necessitate underlining), but under normal circumstances there would be no advantage in using them in preference to System 7 which was significantly more effective. Systems 1,2 and 6 were relatively so ineffective that they are not worth considering when there are better systems which could be used at no extra cost. It would seem therefore that it is possible to produce bibliographical material on a standard typewriter or on an upper and lowercase line printer in such a way as to optimise the ease of use of the material without any significant increase in cost in terms of equipment, paper and binding costs, or time. Even where computer printout is restricted to uppercase only, a spatial coding system such as System 7 could still be used to great advantage.
Acknowledgement This study was conducted as part of a programme of research into the readability of print in information publishing, supported by a grant from the Office for Scientific and Technical Information.
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141