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Adapting computer data storage to user group behaviour
Applied Ergonomics 1981, 12.2, 99-101
Adapting computer data storage to u s e r group behaviour D.J. Cairns and J.J. Florentin Department of Computer Science, Birkbeck College, London
We have designed several interactive computer systems for financial analysts. I n early designs we treated the analyst-computer interactive dialogue at a computer terminal as being isolated from group considerations. In a later system we were forced to make extensive technical changes to take account of data storage sharing. This sharing of data storage had to operate in a way which was consistent with existing group attitudes. The relevant features of this system are described, and reviewed after more than two years of operation. We conclude that many user-computer interactive dialogues cannot be designed as if they were 'private ' to a single user, but must be considered in a wider context of the way in which members of a user group interact.
We have designed several computer systems for financial analysis where analysts access a computer directly through an interactive terminal with a keyboard and display screen. Analysts explore problems, like business forward planning, in a non-routine way; for example, they can display and amend business forward plans repeatedly and very rapidly. In these systems analysts do not write computer programs and deal directly with computer technicalities, but instead the computer operates under the control of programs provided by designers like ourselves. These programs display messages on the screen and invite responses from the analyst. The messages and response procedures can be varied and their design is mainly a human factors issue. Such systems are called 'decision support systems' by Alter (1977). The design of a decision support system raises a wide range of issues pertaining to the place of the computer in a scheme of business activities, but much of our own design effort has concentrated on the interaction between a single analyst and the computer terminal. We treated this interaction as isolated, thus simplifying the design process. Eventually we encountered a particular system where this interaction could not be isolated, and a significant modification in operation was needed because the computer was a shared resource. This paper describes the relevant features of this particular system and draws the general conclusion that there are many occasions when an interaction between a single individual computer user and a computer terminal can only be designed properly when the circumstances of a whole group of other computer users is also considered. Our conclusion reinforces the view that a computer applications system has to be designed as a coherent whole from the human factors standpoint. If ergonomists are brought in to advise on user-terminal interactions then they should not be confined to refining interactions which have already been predetermined by computer systems
0003-6870/81/02 0099-03 $02.00 (~) IPC Business Press
designers. As computer systems designers we are aware of the difficulties caused by having to deal with a fluid design situation, but feel that appropriate methodologies have to be developed to allow such flexibility.
Outline of the computer system Three years ago we designed and installed an interactive investment analysis system. Analysts studied the past and predicted the future of projects as a series of events. Each event had a financial outcome, and the computer calculated the overall financial results of the project. The details of each project were stored in a computer file on a moderately sized disk attached to the computer. An analyst at an interactive video display/keyboard terminal could call up a project by name and then amend its details. Any financial results of the project could also be stored on the computer disk and recalled for reference. During a terminal session an analyst could create several variants of a project, and the new data could be retained in a computer file simply by giving the file a name. When a data file was no longer needed it could be deleted by a special 'Tidy' operation. We were anxious to stop users accidentally deleting f'des which were still wanted, so 'Tidy' was designed as a short terminal session in its own right. We expected users to keep a list of files to be deleted, and then run 'Tidy' in a formal session, perhaps once a week. 'Tidy' first accepted the list of names of files to be deleted, and then came back to the user for confirmation. In addition 'Tidy' effected an archival copy of the deleted data so that it would not be really 'lost'. 'Tidy' took about 20 min to run. No specialist computer staff were involved, so 'Tidy' had to be run by users.
The problem During the first year of operation, users complained that work was being held up by the computer disk becoming full so that new projects could not be stored. It transpiretl
Applied Ergonomics
June 1981
99
that 'Tidy' was only run as a crisis measure, usually when important work had to be done. When important work was waiting to be done, the 20 min delay needed to run 'Tidy' was felt to be intolerable.
produce a new file, also of a specific type. This convention produced an orderly flow of activity, and helped the computer to check that operations took place on appropriate files only.
The simplest solution would have been to buy a much larger disk, but this was not acceptable to the business. We tried to persuade the analysts to run 'Tidy' in a regular and disciplined way but were unsuccessful. Another suggestion for solving the 'disk full' problem was to give each analyst a personal section of the existing disk. Thus each analyst would be responsible for 'Tidy-ing' his personal space. This suggestion was rejected by the analysts because they felt that it was not possible to devise a 'fair' allocation of the disk capacity. There were seven computer users, and three of them were undoubtedly heavier users than the other four. The rejection of this solution caused us to consider more deeply the way that the entire office used the computer.
Different temporary files were set up for each file type. In using computer files the user does not need to remember every detail because the investment system was designed to remember the data context. The data context is the collection of names of the last used file of each type. Knowing that a particular operation is about to be performed the computer is able to offer prompts of the starting file name such as:
An interpretation of the problem Essentially the 'disk full' problem arose because a limited disk capacity was shared amongst the users, and some cooperation was needed to clear unwanted data files. Now, in this particular office, it was not customary for the analysts to cooperate closely. Work was done for many different clients, and analysts worked singly or in temporary groups of two or three on a specific assignment. A manager supervised these assignments, but analysts were much involved in initiating new assignments and were thus not wholly dependent on the manager. In this environment a shared central disk store and our 'Tidy' operation were demanding a degree of cooperation which was not customary.
A solution A solution had to recognise that analysts worked as individuals, and additional data storage had to be cheap. The only feasible approach was to install a diskette unit at the computer terminal. Diskettes are thin plastic disks, permanently kept in a cardboard jacket 8 in (203 mm) square. Ten diskettes can be kept in a box which fits easily on to a bookshelf. Each diskette would hold about six files, and each analyst would keep personal diskettes; they are relatively cheap and so a large number could be kept. The method of working was to be that the analyst placed a diskette into the terminal unit at the beginning of a session. The wanted files were transferred to the computer disk, and the computer could then access them at high speed. New files could be returned to diskettes for long-term keeping. It would have been awkward to use diskettes during a session, so a user was given a collection of temporary files on the computer disk for use during a session; at the end of the session these files were (normally) lost. We were now faced with the problem of designing handling procedures for the temporary files and the diskettes, which again is a human factors issue.
Managing the temporary files In the investment system there were several types of file, for example, project description files and cash flow files. The computer system was designed so that each ol~eration started with a specific type of file, and might later
100
AppliedErgonomics
June 1981
(i) (ii)
the name (number) of the last used temporary file of appropriate type, or the name of the last used diskette file of appropriate type.
The analyst can accept either of these prompts by depressing a single key and thus re-use old files, or can override the prompts with a new diskette file name, or temporary file number, when the old files remain. A similar prompting follows the ending of an operation. The question arose - how many temporary files of each type should be provided? The analysts argued strongly that the number should be very large and, indeed, limited only by the physical computer resources. We argued that it was not practicable for an analyst to keep track of many files, and that too many files would cause confusion. A compromise was reached - we would provide nine files of each type, but initially only two files of each type would be accessible. On being asked we would increase the number of accessible files. After two years of use there are still only two files of each type available; no-one has asked for more.
Managing the diskettes We thought that problems with diskettes might be: • diskettes could be lost or damaged since they were left about in the office; • analysts would not label their diskettes properly, and so would lose track of individual files; • diskettes can be inserted into the terminal unit in eight different ways. In only one orientation will the unit function correctly. To cope with these anticipated difficulties we set the following procedures. • Diskettes have to be used in matched pairs. If a diskette is lost or damaged, it is hoped that the other will remain, and can be copied to make a new mate. The control program enforces the use of matched pairs of diskettes. • A log of usage is recorded on each diskette. The control program fills in the log every time a new file is added to the diskette by recording its name, type, date, and the identifying initials of the analyst. A print-out of the log is easily obtained. • Should a diskette not be working properly then all data in the computer is held in a safe suspended state until the diskette fault is cured. It is possible to initialise a new diskette by logging the owner's name whilst the problem data is held suspended.
Comments The combined diskette - temporary rile system has been in use for over two years. Users needed little training in handling diskettes. We have kept in touch with this office since installation of the diskettes and have had no further comments on data storage, although we have been asked to extend and modify other parts of the system. Our observation is that analysts do not write enough explanatory information on the labels of the diskettes. On one occasion a pair of diskettes was temporarily mislaid, but this did not evoke criticism of the computer system. It is possible that as the number of diskettes in use grows some strain will be felt in handling them, but we have no evidence of this at present.
examplewhere a high quality, but slow, printer was shared between a group of business negotiators. In order to prevent one negotiator holding the printer for a long period of time, and so delaying others, it was necessary to break print operations into small blocks; this affected the interaction design. These small blocks were then interleaved, so that each user obtained some print output quickly. It is now our practice to consider at an early stage the ways in which terminal users can interact by sharing resources, and then investigate how group attitudes affect this sharing.
Acknowledgements
In this example the indentification of the individualistic mode of working was the key observation. We hypothesise that if the analysts had been essentially assistants to a single manager then a single central disk would have been effective.
The authors wish to thank the referees for comments which helped to improve the presentation of this paper, and the Science Research Council for supporting investigations into interactive computer dialogues.
Conclusion
Bibliography
The episode described above made it clear that there are circumstances in which a user-computer terminal interaction has to be considered in the context of the activities of a whole group of users. We have encountered another
Alter, S. 1977 Sloan Management Review, Fall, 39-56. 'A taxonomy of decision support systems'.
OlSPLR, u Technology& Applications the international journal covering developments in both the technology and applications of displays
C o v e r a g e includes: • Digital and a l p h a n u m e r i c displays • G r a p h i c and pictorial displays • Picture p r o c e s s i n g • Systems design • C o m m e r c i a l e v a l u a t i o n of display technologies • N o v e l and d e v e l o p i n g applications • E r g o n o m i c considerations in d i s p l a y d e s i g n and use
For further details complete and return the coupon
I II I I I II I II I II •I
To: Christine Mullins, Displays, IPC Science and Technology Press Ltd, PO Box 63, Westbury House, Bury Street, Guildford, Surrey GU2 5BH England Telephone: 0483 31261 Telex: 859556 Please send me further details on DISPLAYS I would like a sample copy [] Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Organisation and address . . . . . . . . . . . . . . . . . . . . .
AppliedErgonomics
June 1981
101
Adapting computer data storage to u s e r group behaviour D.J. Cairns and J.J. Florentin Department of Computer Science, Birkbeck College, London
We have designed several interactive computer systems for financial analysts. I n early designs we treated the analyst-computer interactive dialogue at a computer terminal as being isolated from group considerations. In a later system we were forced to make extensive technical changes to take account of data storage sharing. This sharing of data storage had to operate in a way which was consistent with existing group attitudes. The relevant features of this system are described, and reviewed after more than two years of operation. We conclude that many user-computer interactive dialogues cannot be designed as if they were 'private ' to a single user, but must be considered in a wider context of the way in which members of a user group interact.
We have designed several computer systems for financial analysis where analysts access a computer directly through an interactive terminal with a keyboard and display screen. Analysts explore problems, like business forward planning, in a non-routine way; for example, they can display and amend business forward plans repeatedly and very rapidly. In these systems analysts do not write computer programs and deal directly with computer technicalities, but instead the computer operates under the control of programs provided by designers like ourselves. These programs display messages on the screen and invite responses from the analyst. The messages and response procedures can be varied and their design is mainly a human factors issue. Such systems are called 'decision support systems' by Alter (1977). The design of a decision support system raises a wide range of issues pertaining to the place of the computer in a scheme of business activities, but much of our own design effort has concentrated on the interaction between a single analyst and the computer terminal. We treated this interaction as isolated, thus simplifying the design process. Eventually we encountered a particular system where this interaction could not be isolated, and a significant modification in operation was needed because the computer was a shared resource. This paper describes the relevant features of this particular system and draws the general conclusion that there are many occasions when an interaction between a single individual computer user and a computer terminal can only be designed properly when the circumstances of a whole group of other computer users is also considered. Our conclusion reinforces the view that a computer applications system has to be designed as a coherent whole from the human factors standpoint. If ergonomists are brought in to advise on user-terminal interactions then they should not be confined to refining interactions which have already been predetermined by computer systems
0003-6870/81/02 0099-03 $02.00 (~) IPC Business Press
designers. As computer systems designers we are aware of the difficulties caused by having to deal with a fluid design situation, but feel that appropriate methodologies have to be developed to allow such flexibility.
Outline of the computer system Three years ago we designed and installed an interactive investment analysis system. Analysts studied the past and predicted the future of projects as a series of events. Each event had a financial outcome, and the computer calculated the overall financial results of the project. The details of each project were stored in a computer file on a moderately sized disk attached to the computer. An analyst at an interactive video display/keyboard terminal could call up a project by name and then amend its details. Any financial results of the project could also be stored on the computer disk and recalled for reference. During a terminal session an analyst could create several variants of a project, and the new data could be retained in a computer file simply by giving the file a name. When a data file was no longer needed it could be deleted by a special 'Tidy' operation. We were anxious to stop users accidentally deleting f'des which were still wanted, so 'Tidy' was designed as a short terminal session in its own right. We expected users to keep a list of files to be deleted, and then run 'Tidy' in a formal session, perhaps once a week. 'Tidy' first accepted the list of names of files to be deleted, and then came back to the user for confirmation. In addition 'Tidy' effected an archival copy of the deleted data so that it would not be really 'lost'. 'Tidy' took about 20 min to run. No specialist computer staff were involved, so 'Tidy' had to be run by users.
The problem During the first year of operation, users complained that work was being held up by the computer disk becoming full so that new projects could not be stored. It transpiretl
Applied Ergonomics
June 1981
99
that 'Tidy' was only run as a crisis measure, usually when important work had to be done. When important work was waiting to be done, the 20 min delay needed to run 'Tidy' was felt to be intolerable.
produce a new file, also of a specific type. This convention produced an orderly flow of activity, and helped the computer to check that operations took place on appropriate files only.
The simplest solution would have been to buy a much larger disk, but this was not acceptable to the business. We tried to persuade the analysts to run 'Tidy' in a regular and disciplined way but were unsuccessful. Another suggestion for solving the 'disk full' problem was to give each analyst a personal section of the existing disk. Thus each analyst would be responsible for 'Tidy-ing' his personal space. This suggestion was rejected by the analysts because they felt that it was not possible to devise a 'fair' allocation of the disk capacity. There were seven computer users, and three of them were undoubtedly heavier users than the other four. The rejection of this solution caused us to consider more deeply the way that the entire office used the computer.
Different temporary files were set up for each file type. In using computer files the user does not need to remember every detail because the investment system was designed to remember the data context. The data context is the collection of names of the last used file of each type. Knowing that a particular operation is about to be performed the computer is able to offer prompts of the starting file name such as:
An interpretation of the problem Essentially the 'disk full' problem arose because a limited disk capacity was shared amongst the users, and some cooperation was needed to clear unwanted data files. Now, in this particular office, it was not customary for the analysts to cooperate closely. Work was done for many different clients, and analysts worked singly or in temporary groups of two or three on a specific assignment. A manager supervised these assignments, but analysts were much involved in initiating new assignments and were thus not wholly dependent on the manager. In this environment a shared central disk store and our 'Tidy' operation were demanding a degree of cooperation which was not customary.
A solution A solution had to recognise that analysts worked as individuals, and additional data storage had to be cheap. The only feasible approach was to install a diskette unit at the computer terminal. Diskettes are thin plastic disks, permanently kept in a cardboard jacket 8 in (203 mm) square. Ten diskettes can be kept in a box which fits easily on to a bookshelf. Each diskette would hold about six files, and each analyst would keep personal diskettes; they are relatively cheap and so a large number could be kept. The method of working was to be that the analyst placed a diskette into the terminal unit at the beginning of a session. The wanted files were transferred to the computer disk, and the computer could then access them at high speed. New files could be returned to diskettes for long-term keeping. It would have been awkward to use diskettes during a session, so a user was given a collection of temporary files on the computer disk for use during a session; at the end of the session these files were (normally) lost. We were now faced with the problem of designing handling procedures for the temporary files and the diskettes, which again is a human factors issue.
Managing the temporary files In the investment system there were several types of file, for example, project description files and cash flow files. The computer system was designed so that each ol~eration started with a specific type of file, and might later
100
AppliedErgonomics
June 1981
(i) (ii)
the name (number) of the last used temporary file of appropriate type, or the name of the last used diskette file of appropriate type.
The analyst can accept either of these prompts by depressing a single key and thus re-use old files, or can override the prompts with a new diskette file name, or temporary file number, when the old files remain. A similar prompting follows the ending of an operation. The question arose - how many temporary files of each type should be provided? The analysts argued strongly that the number should be very large and, indeed, limited only by the physical computer resources. We argued that it was not practicable for an analyst to keep track of many files, and that too many files would cause confusion. A compromise was reached - we would provide nine files of each type, but initially only two files of each type would be accessible. On being asked we would increase the number of accessible files. After two years of use there are still only two files of each type available; no-one has asked for more.
Managing the diskettes We thought that problems with diskettes might be: • diskettes could be lost or damaged since they were left about in the office; • analysts would not label their diskettes properly, and so would lose track of individual files; • diskettes can be inserted into the terminal unit in eight different ways. In only one orientation will the unit function correctly. To cope with these anticipated difficulties we set the following procedures. • Diskettes have to be used in matched pairs. If a diskette is lost or damaged, it is hoped that the other will remain, and can be copied to make a new mate. The control program enforces the use of matched pairs of diskettes. • A log of usage is recorded on each diskette. The control program fills in the log every time a new file is added to the diskette by recording its name, type, date, and the identifying initials of the analyst. A print-out of the log is easily obtained. • Should a diskette not be working properly then all data in the computer is held in a safe suspended state until the diskette fault is cured. It is possible to initialise a new diskette by logging the owner's name whilst the problem data is held suspended.
Comments The combined diskette - temporary rile system has been in use for over two years. Users needed little training in handling diskettes. We have kept in touch with this office since installation of the diskettes and have had no further comments on data storage, although we have been asked to extend and modify other parts of the system. Our observation is that analysts do not write enough explanatory information on the labels of the diskettes. On one occasion a pair of diskettes was temporarily mislaid, but this did not evoke criticism of the computer system. It is possible that as the number of diskettes in use grows some strain will be felt in handling them, but we have no evidence of this at present.
examplewhere a high quality, but slow, printer was shared between a group of business negotiators. In order to prevent one negotiator holding the printer for a long period of time, and so delaying others, it was necessary to break print operations into small blocks; this affected the interaction design. These small blocks were then interleaved, so that each user obtained some print output quickly. It is now our practice to consider at an early stage the ways in which terminal users can interact by sharing resources, and then investigate how group attitudes affect this sharing.
Acknowledgements
In this example the indentification of the individualistic mode of working was the key observation. We hypothesise that if the analysts had been essentially assistants to a single manager then a single central disk would have been effective.
The authors wish to thank the referees for comments which helped to improve the presentation of this paper, and the Science Research Council for supporting investigations into interactive computer dialogues.
Conclusion
Bibliography
The episode described above made it clear that there are circumstances in which a user-computer terminal interaction has to be considered in the context of the activities of a whole group of users. We have encountered another
Alter, S. 1977 Sloan Management Review, Fall, 39-56. 'A taxonomy of decision support systems'.
OlSPLR, u Technology& Applications the international journal covering developments in both the technology and applications of displays
C o v e r a g e includes: • Digital and a l p h a n u m e r i c displays • G r a p h i c and pictorial displays • Picture p r o c e s s i n g • Systems design • C o m m e r c i a l e v a l u a t i o n of display technologies • N o v e l and d e v e l o p i n g applications • E r g o n o m i c considerations in d i s p l a y d e s i g n and use
For further details complete and return the coupon
I II I I I II I II I II •I
To: Christine Mullins, Displays, IPC Science and Technology Press Ltd, PO Box 63, Westbury House, Bury Street, Guildford, Surrey GU2 5BH England Telephone: 0483 31261 Telex: 859556 Please send me further details on DISPLAYS I would like a sample copy [] Name . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Organisation and address . . . . . . . . . . . . . . . . . . . . .
AppliedErgonomics
June 1981
101