Journal of Occupational Accidents, 9 (1987) 87-105

Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands 87

Simulating the Use of a Computerized Injury and Near Accident Information System in Decision Making

URBAN KJELLfiN*

Department of Work Science, Royal Institute of Technology, S-100 44 Stockholm (Sweden)

(Received 10 November 1986; accepted i4 January 1987)

ABSTRACT

KjellCn, U., 1987. Simulating the use of a computerized injury and near accident information system in decision making. Journal of Occupational Accidents, 9: 87-105.

The use of information from long time experience about occupational injuries and near acci- dents in the decision making has been simulated. The objective has been to study the feasibility of making information about these types of occurrences available to decision makers at various parts of a company via a computer. Prototype computerized injury and near accident information systems were developed at two companies; an airline and a steel mill. Twenty-seven subjects from the line and safety organizations and from the technical, personnel, and health and safety staff at these companies participated in the simulations. A total of more than 100 “decisions” concerning proposals for health and safety measures were made during the simulations. Results showed that the various categories of subjects indicated different information needs in making decisions; infor- mation about injuries and near accidents at the company had a high priority for all categories of subjects except one (technical staff). The identification of reports of relevance to a proposal and the display of parts of the contents of these reports represented a frequent use of the information systems; black-spot-analysis, i.e., the identification of concentrations of injuries and near acci- dents represented another frequent use. A relatively small fraction of the total number of available observations about each injury or near accident was actually used in the “decision making”. The results demonstrated needs of free text descriptions of observations as well as of coded informa- tion. Differences between the results from the two companies indicate that the solutions regarding computer support should be adapted to the characteristics of the individual company. Implica- tions of the results for the design and implementation of computerized injury and near accident information systems are discussed.

INTRODUCTION

Evaluation research into corporate safety practice has revealed a number of weaknesses in the injury and near accident information systems (Kjellkn and

*Correspondence should be sent to: Dr. U. KjellBn, Norsk Hydro A/S, P.O. Box 200, N-1321 Stabekk, Norway.

0376.6349/87/$03.50 0 1987 Elsevier Science Publishers B.V.

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Menckel, 1986). This applies especially to the distribution and use of the infor- mation in the decision making. For example, two studies showed that accident reports as well as statistical summaries of accidents rarely were used as a basis for decisions about remedial actions (Edwards, 1981; Kjellen, 1982).

Accident research has focused on methods of reporting and investigating into injuries and near accidents. Experiments at various companies show that it is possible to improve the quality of investigations, analyses and follow ups of individual occurrences of this type (Merit et al., 1976; Kjellen, 1983; Menckel and Carter, 1985). On the other hand, the research into the use of information about injuries and near accidents in the decision making has been fragmentary. As a consequence, systematic knowledge is lacking in how to establish chan- nels for the reliable and efficient distribution of information to decision mak- ers; in particular, knowledge is lacking in how to make the collect,ed information from long time experience about these occurrences available to decision mak- ers when the information is needed.

Chmputer support in safety practice

Computer technology provides a possible solution to the problem of infor- mation distribution. For example, it is possible to store “complete” informa- tion about injuries and near accidents in a computer, and to recover such information as may be of interest in each individual case. An increasing num- ber of companies have sufficient computer experience to apply the solution.

Various types of computerized accident information systems for use inside companies are described in the literature (Adams et al., 1981; Colvin, 1984; Rosness, 1986). However, there is a general lack of systematic documentation of the effects of these systems on decision making.

The present stud?’

A cooperation between the Royal Institute of Technology and two compa- nies ( an airline and a steel mill) made it possible to simulate the use of infor- mation about injuries and near accidents in decision making. The objective was to study the feasibility of making information about these types of occur- rences available to decision makers at various parts of a company via com- puters. The study had a number of specific goals: l to map the information needs of various categories of decision makers in

injury cant rol; l to map requirements regarding the contents of a data base on injuries and

near accidents, especially regarding the size of the dat,a base, t,ypes of obser- vations about injuries and near accidents, the quality and degree of struc- turing of the data;

l to map other requirements regarding the design and introduction of com-

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puter support, including hardware and software solutions, and organization, routines and educational needs related to the use of the information system. The separate studies at each company have been reported elsewhere ( Kjel-

l&n, 1985; Kjellen, 1986a; Kjellen, 1986b). This paper is based on the accu- mulated results from the two companies. It focuses on patterns that are revealed through comparisons of the resuhs from the two companies and of the results from different categories of decision makers.

METHOD

At the airline as well as at the steel mill, the initiative to participate in the study was taken by the safety department. The results were intended for use inside the companies in decisions to introduce computer support in safety practice.

The Swedish ground organization of the airline (about 5800 employees) was involved in the study. Two thirds of the employees were white collar workers. Approximately 100 occupational injuries were reported each year; 40% of these resulted in absence from work. Near accidents were not reported on a routine basis.

Five departments of the steel mill participated in the study; three production departments (steel manufacturing, continuous casting and materials han- dling) and two maintenance departments (brick laying and mechanical main- tenance) . About 500 blue collar workers and 30 supervisors were employed at these five departments. About 60 occupational injuries and about the same number of near accidents were reported each year from these five departments. Half the reported injuries were of a lost time type.

Both companies had a well developed safety organization, including health and safety departments and safety committ.ees. At the airline, investigations into injuries were carried out by especially appointed officers; at the steel mill first line supervisors had this responsibility, and the results were scrutinized by the safety department. At both companies, investigations into injuries were document,ed on the official form for not,ifying the National Social Insurance Board (here called NSIB-form, see Statistics Sweden, 1984). Near accidents occurring at the steel mill were reported on a company form.

The safety departments of both companies made periodic summaries of the injury statistics. These summaries and the cont.ents of individual reports were distributed to the safety committees, the line organization and the safety rep- resentatives of the workers. The uses of this information included: follow ups of individual reports; the setting of priorities regarding safety activities; and the setting of goals regarding t,he level of safety.

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Ikuelopment of the prototype systems

At each company. a prototype computerized injury and near accident infor-

mation system was developed. Each system consisted of two parts: (1) a gen-

eral so called information retrieval system ( IR-system 1; and ( 2 1 an application

specific data base ( i.e. a data base on occupational injuries and near accidents

from the company 1. The IR-system BASIS was selected for the study (Battelle. 1981). It pro-

vides means for processing information from documents, including: (a) col-

lection and storing of various types of data from documents ( numerals, coded

data. free text descriptions) : (b ) searching for documents that fulfill certain

conditions: and ( c ) retrieval, analysis, and presentation of information from

these documents. Each system was installed on a central computer and was

accessed via a terminal at the company. This technical solution was selected

in order to minimize development work and restrictions regarding the ret,rieval,

analysis and display of information. The user friendliness of thejnformation

system and the graphical quality of the output were regarded to be less critical

in this application.

The development work at each company consisted of specifying the data

base, supplementing the information in the injury and near accident reports.

and feeding the computer with the available information.

The specification of each data base was made by a group, consisting of a

safety engineer from the company, a computer consultant and a researcher.

The types ofobservations to describe each injury or near accident were defined,

and means of’ storing data about these observations were specified.

It was decided that all relevant observations from the NSIB-form (36 in

numl)er ) and supplementary information about administrative conditions (3 addit ional observations) and about the sequence of events ( 2 additional obser-

\.ntions) should be included in the data bases. Administrative personnel of the safety departments Lvere responsible for supplementing the information in the

reports concerning administrative conditions. At the airline, a safety engineer

provided supplementary information about the sequence of events; this task

\vas carried out by supervisors and safety representatives at the steel mill, and

the results were strut inized by a researcher.

The data base of the airline consisted of observations about 150 injuries (120 accidents and 30 occupational diseases) from the period January 1,

19KSDecember 31, 1984; the data base of the steel mill consisted of observa-

t ions about 180 injuries (144 accidents and 36 occupational diseases) and 138 near accidents, from the period January 1, 1983-June 30, 1985.

Table 1 shows a selection of the observations of the data bases that were

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TABLE 1

Types of observations about injuries and near accidents that were included in the data bases and subsequently used in the simulations

Type of observation Source Response rate ( 5 )

Airline Steel mill

Coded data

Report ID-number Type of report (accident, near

accident, disease) Date of reporting Date of occurrence Time of occurrence Age of victim (1) Numbers of years in present

occupation (1)

How long at the company (1) Department Adequate education? (1) Adequate information? (1) Adequate job experience? (1) Working hours (1) Part of body injured (1) Nature of injury/illness (1) Number of days of absence (1) Type of machine/materials (1) Type of injury inflicting energy

Semi-structured data

Occupation of victim (1) NSIB 98 97

Place of occurrence NSIB 95 85 Activity of victim NSIB 73 75 Type of machine/materials NSIB 48 35 Deviations (2) See Fig. 1 27 40 Description of injury (1) NSIB 82 76 Contributing factors NSIB 24 38 Immediate measures NSIB 62 43 Long-term preventive actions NSIB 22 11

~instructured data

Sequence of events NSIB 100 100

Company Company

NSIB 95 96

NSIB 92 99

NSIB 82 89

NSIB 100 100 NSIB 88 80

NSIB Company NSIB NSIB NSIB NSIB NSIB NSIB Company NSIB See Fig. 1

100

100

99

100 95 83 88 94 98 92 -

68 100

100

100

91

100 94 85 90 92 98

100 90 70

100

Coded data are represented by numerals or a fixed number of classes. Semi-structured data are represented by free text descriptions of specific observations. The table also shows the response rate for accidents, i.e., the relative number of reports for which information on the observation was available. (1) Not documented for near accidents. (2) Deviations were documented for the accidents from one year at each company.

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CONTHIBUTING FRCTORS

- design c7f war-kplace/equlproer,t

- urgan1zat 1or1 of war-k

- method of war-k

DEVIFlTIONS FROM UNCONTRULLED

THE NORM FOR THE FLOW OF ENERGY INJURY

FFIULTLESS F’RUDUCTION

PROCESS

Lack cmf Lc*55 C\f Body exposed

cant r-01 cor,t PO 1 t cl ener-gy

) Time car-bltr-a*-y scale)

Fig. 1. Model of the accident process (Kjelldn, 1986a). The model represents a synthesis of earlier models: the energy model (Haddon, 1968) ; the ISA-model (Statistics Sweden, 1984); and the

deviation model (Kjellkn and Larsson. 1981; Kjellkn, 1984).

actually accessed during the simulations. Observations concerning the sequence of events were defined in relation to a model of the accident sequence (Fig. 1)

A total of 27 persons participated in the simulations; 13 at the airline and 14 at the steel mill. The subjects were selected by a safety engineer at each com- pany in order to represent various potential user groups of a computerized injury and near accident information system. Table 2 shows the distribution of subjects with respect to type of function within the company.

Except for safety representatives, subjects typically had a college or univer- sity degree in technology. Subjects representing health and safety staff, super- visors and safety representatives were exposed to information about injuries and near accidents on a routine basis; subjects representing technical and per- sonnel staff functions, on the other hand, did not have this experience.

Outline of the simulations

The use of computer support in decisions to prevent occupational injuries was simulated in a two hours’ interviewing session with each subject. The ses- sions followed a step-by-step procedure: (1) The subject was interviewed about his area of responsibility, his span of

authority, and his access to health and safety related information.

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TABLE 2

Distribution of subjects with respect to type of function and company

Type of function

Line organization (operation and maintenance)

Technical staff (purchase, design, planning, quality assurance)

Personnel staff (planning, education )

Health and safety staff Safety representatives of the

workers

Number of subjects

Airline Steel mill

4 4

5 3

1 2

1 2 2 3

Total

8

8

3

3 5

Summary 13 14 27

(2) The subject was asked to propose measures within his area of authority/re- sponsibility in order to improve health and safety at the work places.

Depending on the time available, “decisions” were made on all or a selection of the subject’s proposals, one at a time. The decision-making process included three steps (3 to 5 ) . (3)

(4)

(5)

(6)

The-subject was asked to identify his general information needs and his needs of information about injuries and near accidents in order to allow a decision on the design and implementation of the proposal to be made. The information needs concerning injuries and near accidents were trans- lated into a question to the data base. The data base was accessed in order to generate answers to the question. The researcher functioned as an inter- mediary between the subject and the computer in this step. All commu- nication with the computer was documented on a diskette for future analysis. The answers were assessed by the subject and he was asked to make a “decision” on the proposal. The subject was finally asked about his needs of access to an injury and near accident information system.

RESULTS

Types of proposals

A total of 134 health and safety measures were proposed by the subjects; 65 at the airline and 69 at the steel mill. The number of proposals per subject varied between one and eight. With few exceptions, the proposals were of a

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TABLE 3

Distribution of proposals for the different categories of subjects

Type of proposal Type of function

Line

organization

(5%)

Technical

staff ( 5% ) Personnel

staff ( % ) Health 6i

Safety

staff

( 96 )

Safety

representative

(96)

Technical change

General 22

Traditional 8

health & safety

Organizational change

General 32

Traditional 24

health & safety

Other

Discipline 5

Correction of 8

deviations

50 0 12 26

28 0 24 15

5 31 6 7

10 69 59 44

0 0 0 7

8 0 0 0

Number of

proposals

37 40 13 17 27

The table is based on a total of 134 proposals.

General technical changes: layout, design of equipment, method of work and work material. Tra-

ditional technical health and safety changes: fixed and personal protective equipment. General

organizational changes: work organization, manning, activity planning, system of shift, time of

work. Traditional organizational health and safety changes: safety instructions, training, safety

inspections.

long term nature and involved technical or organizational changes. At both companies, approximately the same number of technical and organizational measures were proposed. Subjects representing technical, personnel and health- and-safety staff functions typically focused on fewer categories of measures, as compared to subjects representing line management and safety represen- tatives (Table 3 ).

Information needs in decision making

One hundred and twenty-three of the proposals were assessed with respect to general information needs in order to allow a decision to be made (Table 1). All categories of subjects except those representing technical staff func- tions most frequently identified needs of information about injuries and near accidents. Subjects from technical staff, on the other hand, most frequently indicated needs of information about health and safety standards. All cate-

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TABLE 4

Relative share of the proposals of each category of subjects for which the different types of infor- mation needs were identified by the subjects

Information need (type of source)

Type of function

Line Technical Personnel Health & Safety organization staff ( % ) staff (% ) Safety representative

(%) staff (%I (%o)

Internal

Injury/near accident reports

Health and safety measurements and studies

Technical studies Employees

41

15

9 24

External

Safety standards 6 Product information 9 Research and development, 0

other companies’ experience

Number of proposals for which information needs were identified

34 36 10 17 26

11

12

0 0 0 12

25 20 24 15

44 10 12 15 17 10 12 8

0 10 12 8

40

30

35

18

42

25

The table is based on a total of 123 proposals. More than one information need could be identified for each proposal.

gories of subjects frequently referred to needs of information about the atti- tudes of the employees affected by the measure.

Subjects from the steel mill most frequently indicated needs of information about injuries and near accidents; subjects at the airline were, in general, more concerned with information about health and safety standards. This difference probably reflects the importance of regulatory requirements in the day-to-day activities of the airline.

For 110 of the proposals, a subject and the interviewer jointly specified a question to the data base; 62 such questions were specified at the airline and 48 at the steel mill. An analysis of the questions shows that, in general, there were three different types of needs of information about injuries and near acci- dents: (1) the number of reports on injuries and near accidents with specific characteristics and the contents of the individual reports (62 questions); (2)

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identification of concentrations of injuries or near accidents, i.e. black-spot- analysis (38 questions); and (3) distribution of injuries with respect to spe- cific observations (10 questions). Information about distributions of injuries was typically used in “tests of hypotheses” regarding relations between the risk of injury and such variables as age of victim, job experience and time-of-day. The relative number of times that each type of information need was addressed was approximately the same for both companies as well as for the different categories of subjects.

The use of the information systems

The use of the information systems involved, in principle, two types of activ- ities. A subset of reports with certain characteristics in common was delimited on the basis of one or more observations (searches ) . Subsequently, parts of the contents of reports of this subset were displayed. These two steps were repeated until the subject determined that no further analysis was necessary.

At the two companies a total of 195 searches were made; i.e. in average 1.8 searches per question. About 60% of the searches involved coded observations (cp. Table 1) . These were the simplest types of searches.

Example: A supervisor at the steel mill wanted to study reports relating to falling objects from cranes. In step one of the analysis, the distribution of all reports with respect to the observation “TYPE OF ENERGY" was displayed. A subset of 56 reports fulfilling the condition “TYPE OF ENERGY = STRUCK BY

FLYING OR FALLING OBJECT" was created. Subsequently, these reports were analyzed with respect to “TYPE OF MACHINE".

About an equal share of the searches (60% ) involved semi-structured obser- vations and were consequently of a free-text type (cp. Table 1) . These searches were more complicated than searches of coded observations. For example, at the steel mill three different terms were used to denote electricians. The IR- system was equipped with functions that made an efficient search for synon- yms possible. The free-text description of the sequence of events was addressed in about 20% of the searches.

Two types of displays were used in the analyses; i.e. displays of the contents of individual reports (about 3/5 of the displays) and frequency distributions of subsets of reports with respect to certain observations ( 2/5 of the displays). On an average, 1.6 displays were made for each question.

The search-and-display patterns regarding the 110 questions to the data bases have been analyzed with respect to various factors.,

Type of company: There were differences between the two companies with respect to the number and types of searches. About two thirds of the questions at the airline were answered by one search and a subsequent display of the results. The corresponding figure for the steel mill was less than one third. Further, different search strategies were employed at the two companies. At

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TABLE 5

Rank order of types of observations with respect to the number of times that they were addressed in searches or displays at the two companies

Rank order Searches

Airline Steel mill

Displays

Airline Steel mill

1. Occupation of victim

Department Sequence Activity of of events victim

2.

3.

Type of Type of Place of Sequence machine energy occurrence of events

Sequenceof Sequenceof Type of Type of events events machine report

4. Type of Place of Activity of energy occurrence victim

Number of days of absence

5.

7.

Type of Description Type of machine of injury energy

Type of Nature of Type of report injury machine

8. Deviations

9. Nature of injury

The table only shows those types of observations that were involved in 10% or more of the sear- ches/displays at each company.

the steel mill, the first search in a sequence of searches in order to answer a question typically only involved coded observations (71% of the “first searches”). The majority of the subsequent searches addressed coded as well as free-text observations. At the airline, free-text observations were addressed in a majority of the first as well as the subsequent searches. These two differ- ences can be explained by the fact that the data base of the steel mill was about three times as large as the data base of the airline.

At both companies, the searches and displays concerned a relatively small fraction of the 42 different types of observations of the data bases. At the air- line, 34 of the observations were accessed in less than 10% of the searches or displays: the corresponding figure for the steel mill was 32. Differences were found between the companies concerning the types of observations that were addressed in the searches (Table 5). At the airline, the injured person’s occu-

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TABLE 6

Three examples of results of searches with respect to the number of “hits”

Search concept Company Type of observation Total

number of

Type of Sequence of hits

machine events

(number of (number of

hits) hits)

“Crane” Steel mill 7 32 32

“Truck” Airline 2 4 4

“Post” Airline 2 7 7

The aim of the searches was to identify reports concerning: crane accidents; truck accidents; and

accidents involving equipment from the Postal Administration.

pation was frequently addressed in the delimitation of the relevant subset of reports; at the steel mill the work-place code played this role. This difference can be explained by the fact that the data base of the airline included reports from various geographically separated locations with similar types of activities. The occupation of the victim served as a common denominator in the identi- fication of injuries and near accidents of a specific type of activity.

Other types of observations were employed relatively frequently in the searches at both companies. Table 5 also shows the rank order of types of observations with respect to the number of times that they were addressed in displays.

Type of question to the data base: Searches and displays of semi-structured observations occurred in a majority of the analyses of individual reports as well as in a majority of the black-spot-analyses.

Example: A safety engineer needed information to support a decision to implement maintainability analyses in the design of work places. A black-spot- analysis of injuries among maintenance personnel at the continuous casting machines was carried out. Out of 31 reports, 10 involved changes or inspections of rolls. This concentration was identified by analyzing “the activity of the victim”. It would not have been possible to identify the concentration on the basis of coded observations.

Searches of the free-text description of the sequence of events: The free-text description of the sequence of events held an unique position among the “observations” in that it contained various types of information. The searches of the sequence of events proved efficient in identifying documents that searches of other types of observations had failed to identify due to a low response rate ( Table 6, see also Table 1) .

Certain types of occurrences were only possible to retrieve by searching the sequence of events. Examples of such occurrences that were identified during

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the simulations are “slipping’‘-accidents and occurrences involving “water- leaks”.

The “simple”searches: Out of 110 questions, 25 were answered by one search of a single observation. In one third of these searches, the variable “Type of machine/materials” was addressed. The subject typically belonged to the tech- nical staff and the information needed as a basis for design or purchase. Another third of the “simple searches” involved “The occupation of the victim”. In this case, the information was typically intended for use in the design of training and instruction programs. Other examples of variables that were addressed in “simple searches” were “Deviation” and “Type of injury inflicting energy”.

Example: A safety representative wanted to evaluate the relevance of safety inspections. All reports involving technical deviations were identified and a list of these deviations was displayed. After scanning this list, the subject con- cluded that only a small fraction of these deviations were looked for in safety inspections. He “decided” that the direction of safety inspections had to be re- evaluated.

The subjects “decisions” on the proposals

The answers from the computer concerning the 110 proposals were assessed by the subjects. For 30% of the proposals, the subjects’ assessments were that the related health and safety measure should be implemented. This share was approximately the same for technical and organizational measures. The figure was higher than average for subjects representing personnel staff (67% ) and safety representatives (45% ). For 44% of the proposals, the subjects’ assess- ment were that the answer supported a decision to drop the proposal. A higher than average ratio of this assessment was found among subjects representing technical staff (54% ) and line management (52% ) .

In about a quarter of the cases, the subjects were not able to make a “deci- sion”. This outcome was relatively more common among subjects representing health and safety staff. The subjects were asked to further comment on this conclusion. It was justified, for example, by a poor quality of the information in the data bases, by a poor reliability in the reporting of injuries and near accidents, and by a lack of other types of information such as cost-figures and the attitudes of the employees to the proposal.

There were also differences between the two companies. Whereas about half of the proposed measures at the steel mill were assessed by the subjects to be justified, the corresponding figure for the airline was about a fifth. A difference between the companies in the same direction was also found when the assess- ments of each of the various categories of subjects were compared. Plausible explanations for these results are differences between the companies concern- ing the risk of accidents and the size of the data base. At both companies, the

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subjects were unable to make a “decision” regarding about a quarter of the

proposals.

The subjects’ assessments of the answers from the computer have been ana-

lyzed with respect to type of question. More than half of the results of black-

spot-analyses justified an implementation of the proposed measure; the cor-

responding figure for analyses of individual reports was about a fifth. Five out

of ten distribution-analyses were not sufficient to support a decision to be made.

Needs of access to a computerized injury and near accident information system

Twenty-two out of 27 subjects answered “yes” to the question whether they

needed to have access to a computerized injury and near accident information

system; 17 subjects indicated needs of direct access via terminal at their office.

One subject from line management,, three from the technical and one from

personnel staff answered “no” to the question. Examples of justifications of

this answer were a low utility of the information, that the manual system was

adequate and that t,he health and safety department provided all necessary

information.

DISCUSSION

The intended uses of the results from each of the two participating compa-

nies have primarily been inside companies of a similar size and type of pro-

duction. In this paper, the results from the two companies have been pooled

for the purpose of drawing more general conclusions. However, various factors

restrict the possibilities of generalization. These include, for example, the spe-

cial attributes of the companies studied, the non-random selection of subjects,

and the artificiality of the simulations of the decision-making process. On the

other hand, there are similarities as well as differences in the results between

the two companies and between the various categories of subjects that can be

given meaningful interpretations. Further case studies, for example, involving

evaluations of the use of computer support in safety practice on a routine basis,

are needed in order to verify whether the results are more generally valid.

Here, the implications of the results for the design and implementation of

computer support in safety practice are discussed.

Information needs

Results show that the various categories of subjects had different informa-

tion needs in preventing injuries; information about injuries and near acci-

dents constitutes a significant part of t.his need. These results point at the

importance of a comprehensive approach in analyzing needs of computer sup-

port in safety practice and in the actual design of hardware and software solu-

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tions. For example, the needs of computer supported access to applicable codes, standards and regulations should be assessed as well.

There are various uses of information about injuries and near accidents (see Johnson, 1980). Here, the use of information from about two years’ experience of injuries and near accidents in the decision making has been studied. Indi- cations are that the identification of relevant injury and near accident reports and the display of extracts of the contents of each of these reports represents an important use of the information in this context. An other important use is the identification of concentrations of injuries or near accidents; i.e., black- spot-analysis. The testing of hypotheses concerning relations between the risk of injury and various types of variables such as the age of the victim or the time of the day, could be expected to play a less significant role in this context. At the two companies, limitations regarding the size and quality of the data bases made these types of analyses uncertain.

The design of the database

Only a relatively small fraction of the available observations on injuries and near accidents were actually used in the decision making. Single observations played a basic role in the first screening in order to identify relevant reports; these were not necessarily the same for the two companies. At both companies, a few other types of observations (including the free-text description of the sequence of events) were frequently addressed in searches as well as in displays.

The fact that a researcher functioned as an intermediary between the sub- jects and the computer has implications for the interpretation of these results in particular. A more differentiated pattern of usage can be expected, when various categories of decision makers use a data base of this type on an indi- vidual basis. On the other hand, decision makers cannot be expected to com- prehend and make use of more than a few types of information about injuries and near accidents (cp. Brehmer, 1981) . The study has demonstrated typical types of information that satisfy the information needs concerning a great variety of decisions.

The results demonstrated benefits as well as difficulties in the use of struc- tured and coded observations. Coded observations proved valuable in cases where a relatively high number of reports were processed. This was frequently the case at the steel mill, with its relatively large data base. On the other hand, a low response rate of selected observations of a structured or coded type resulted in a poor reliability in searches for reports. The relevant information could be documented in a less structured way, i.e. in the free-text description of the sequence of events; it was as a consequence more difficult to retrieve.

Black-spot-analyses were carried out on the basis of coded as well as free- text descriptions of observations. In the latter cases, the categorization of the information was carried out by the subject on the basis of the output from the

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computer. This was made feasible through powerful computer capabilities in

delimiting, sorting and summarizing the relevant information.

These different results have implications for the design of a data base on

injuries and near accidents. The data base should contain relatively few obser-

vations. This will allow a concentration of efforts to establish and maintain an

acceptable quality of the input to the data base. The data base should contain

free text descriptions of structured observations as well as of the sequence of

events; in addition, a selection of these observations should be coded.

A computer system with powerful free-text search capabilities was employed

in the study. The needs of structuring and coding the information input to the

comput,er will increase, if less powerful computer systems are utilized.

Introduction of computer support

Earlier research shows that a number of conditions regarding economy,

organization, motivation, knowledge etc. must be fulfilled in order for the

introduction of computerized decision support systems to be successful C Keen

and Morton, 1978). The solutions should be tailored to the specific character-

istics of the company in question. The approach that was selected in the pres-

ent study involved the building up of knowledge and experience on a powerful

prototype system utilizing existing resources, i.e. a general purpose IR-system

and injury and near accident reports. Experiences showed, that this approach

involved the following advantages: low initial investments in hardware and

software; changes to the system and addition of new functions were relatively

easy to accomplish; possibilities of processing data of varying quality and degree

of structuring; extensive possibilities of retrieving and summarizing informa-

tion. Further, the various user groups became more able to define their infor-

mation needs and requirements regarding computer support. A further

advantage is that know how and motivation to use the solutions are promoted

by the application of this type of development strategy (cp. Morris, 1979).

Results indicate that different approaches should be used in introducing

computer support to the various categories of users. Subjects from the health

and snfet?, stuff at the two companies were experienced in the use of informa-

tion about injuries and near accidents. This potential user group could be

expected to build up sufficient knowledge and experience to be able to utilize

the full potential of the information system; results also indicate that it will

call for possibilities of advanced analyses. Consequently, the responsibilit,y for

maintaining and developing the information system and associated analytic

tools should be allocated to this group.

The line organization and the safety representatives were two potential user

groups with similar needs as well as experiences regarding the use of infor-

mation about injuries and near accidents. An obstacle to the introduction of

103

computer support among these groups is the great variety of questions regard- ing injuries and near accidents that they can be expected to put.

Subjects from technical andpersonnel staff fu~tio~s represent potential user groups with little experience in using information about injuries and near acci- dents in the decision making. It could be wise to introduce computer support among these groups by satisfying well defined and relatively uncomplicated information needs. Indications from the study are that this type of information needs is to be found among designers, buyers and educators.

Cost-benefit considerations

The existing routines at the two companies ensured t~hat the reports on inju- ries and near accidents were distributed to decision makers of the line and safety organizations. As compared to these manual routines, the study dem- onstrated a number of potential benefits of new routines involving computer support in improving the quality of decisions by making information about injuries and near accidents more easy to access: l The computer had the capacity of extracting relevant information from large

quantities of data about injuries and near accidents. The relative advantage of computer support increases with the size of the data base. The output. from the data base of the steel mill more frequently justified the implemen- tation of health and safety measure. This data base was two times as large as the data base of the airline.

l The computer made it possible for line managers and safety representatives to access experiences from other departments.

l The computer made experience about injuries and near accidents available to new categories of decision makers. In general, the generation of information from long-term experience repre-

sented a neu! use of this type of information at the companies. All functions that were carried out by the computer are possible to realize by manual meth- ods; experience shows that this is not feasible in practice.

A cost-benefit analysis should include assessments of the effects of this improved basis for decisions on the costs of accidents as well as on the costs of remedial actions. The analysis should also include assessments of the costs of introducing and maintaining a computerized information system of this type, as compared to the costs of maintaining the manual routines.

CONCLUSIONS

Long-term experience about injuries and near accidents represents an important basis for decisions in injury control at corporate level. Computer support provides a feasible means of making the relevant information about these occurrences available to the various categories of decision makers at the

104

right time. The solutions to computer support should make it possible for the decision makers to retrieve individual reports of relevance and to display a selection of the contents of the reports; it should also be possible to identify concentrations of injuries and near accidents. In order for the solutions to become an effective tool in injury control, they should be adapted to the char- acteristics of the individual company. The method that has been applied in the study represents an appropriate means for use inside companies in the speci- fication of criteria regarding the design of computerized injury and near acci- dent information systems.

ACKNOWLEDGMENTS

The work described here was supported by the Swedish Work Environment Fund, SAS, and Svenskt St51 AB. The author is grateful to Mr. Anders Kamb, SAS and Mr. Lennart Spjuth, Svenskt Stal AB, for support and cooperation in establishing the data bases and in planning the simulations. The author is also indebted to Mr. Lennart Persson, Control Data AB and Mr. Bj&n Rosen- gren, University of Stockholm, for advice and support in designing the study and in establishing software solutions.

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