20  Monthly Labor Review • August 2008

Workplace Injuries and Illnesses

Examining evidence on whether BLS

undercounts workplace injuries and illnesses

The BLS Survey of Occupational Injuries and Illnesses offers many

 advantages over other data systems, and BLS has been working 

on improvements to increase its accuracy and scope; nevertheless, 

there is a debate about whether the survey undercounts injuries 

and illnesses to any significant extent

The BLS Survey of Occupational Injuries and Illnesses (SOII or Survey) has 

come under criticism for undercounting the number of injury and illness incidents 

in the workplace. Estimates of the undercount 

range widely from 20 percent to 70 percent 

of all cases in some research. However, other 

research and analysis concludes that the size 

of the undercount is small. This article summarizes and critiques some of these studies 

and describes BLS efforts to better understand 

and address the undercount issue.

SOII produces annual estimates of counts 

and rates (number of cases per worker) of new 

workplace injuries and illnesses. The survey 

data are provided by responding employers, 

who draw information from Occupational 

Safety and Health Administration (OSHA) 

logs and supplementary materials maintained 

by employers throughout the year. SOII is 

separate from other systems for recording 

workplace injuries and illnesses, (hereinafter 

referred to as “data systems”) including workers’ compensation, trauma registries and other 

administrative and survey data sources.

Four dimensions of a potential undercount 

that can be identified are the failure to count 

1. most occupational illnesses that have

a long latency period;

2. occupational injuries and illnesses 

John W. Ruser

John W. Ruser is

the Assistant Commissioner for Safety,

Health, and Working

Conditions in the Office of Compensation

and Working Conditions, Bureau of

Labor Statistics.

E-mail: ruser.john@

bls.gov

 incurred by out-of-scope workers 

 (public-sector workers, the self-

 employed, and workers in households

 and on small farms);

3. some occupational injuries and 

 illnesses that are reported in other 

 data systems such as workers’ com-

 pensation; and

4. some occupational injuries and 

 illnesses that are not reported in any 

 data system.

The Bureau of Labor Statistics takes the allegations of underreporting seriously and has 

instituted a number of activities to understand 

and, where possible, address the issue. First, 

in 2007 BLS conducted a quality assurance 

survey which indicated that SOII data collection processes did not result in an undercount 

along any of the four dimensions listed earlier. 

Second, BLS is extending the scope of SOII to 

include all public-sector workers.

Third, BLS has instituted a program of research to examine and extend previous research 

into the undercount. The aim is to determine 

whether certain types of cases and respondents 

display greater evidence of apparent undercounting and to identify the factors that might 

be responsible for the undercount findings. 

The latter factors include legitimate differences among data systems and methodological 
Monthly Labor Review • August 2008  21

aspects of undercount research that might provide biased 

estimates of the SOII undercount. Fourth, BLS is undertaking focused interviews of employers to learn about decisions made to report injuries and illnesses on OSHA logs 

and to other data systems. Finally, BLS is exploring partnerships with other organizations, including the National 

Institute for Occupational Safety and Health, to research 

the use of alternative data sources to complement the data 

available from SOII.

Although BLS will make progress in addressing the 

undercount issue, it must be conceded that some aspects 

of this issue cannot be addressed within the framework 

of the BLS Survey. Estimating the number of long-latent 

occupational illnesses is not possible with an employerbased recording mechanism. Self-employed, household 

and small-farm workers remain outside the scope of SOII

because they are not part of the SOII sample frame nor are 

they covered by the Occupational Safety and Health Act 

of 1970. In addition, there are a variety of incentives that 

affect the reporting of workplace injuries and illness to 

SOII and other data systems. These incentives are outside 

of BLS control. Estimating cases that are outside the scope 

of SOII (either because they are not OSHA recordable or 

are incurred by out-of-scope workers) may be feasible using other data sources.

This article discusses the SOII undercount issue. After 

providing a brief overview of SOII and some alternative 

data systems, it describes in depth the four different dimensions of the potential undercount. Some of the key 

papers in the undercount literature are summarized. The 

article then discusses a variety of possible reasons for the 

undercount findings, including methodological issues, incentives for reporting, and differences in various data systems. Finally, the article summarizes BLS activities aimed 

at addressing the undercount issue.

Data collection

SOII is a Federal and State program in which employers’ 

reports are collected annually from about 176,000 private-industry establishments.1

 Data are collected starting 

in January after the end of the survey reference year. Responding employers provide information on the number 

of workplace injuries and illnesses by copying the data 

from their Occupational Safety and Health Administration (OSHA) recordkeeping logs to the SOII questionnaire. 

Employers also provide the number of employee hours 

worked (needed in the calculation of incidence rates) as 

well as the establishments’ average employment. 

Besides reporting injury and illness counts, survey respondents are asked to provide additional information for 

a subset of the most serious nonfatal cases logged, namely, those which involved at least 1 day away from work 

beyond the day of injury or onset of illness. Employers 

answer several questions about these cases, including the 

demographics of the worker disabled, the nature of the 

disabling condition, and the event and source producing 

the condition. 

Most employers use information from supplementary 

recordkeeping forms and State workers’ compensation 

claims to fill out the Survey’s “case form”; some, however, 

attach those forms when their narratives answer questions 

on the case form, an option the Bureau offers to help reduce respondent burden. Also, to minimize the burden 

on many larger employers, sampled establishments that 

are projected to have numerous cases involving days away 

from work are instructed to report on a sample of those 

cases. These employers are assigned a range of dates and 

are instructed to provide information only on the cases 

with days away from work for which the date of injury or 

onset falls within the assigned range of dates.

SOII receives occupational injury and illness data from 

the U.S. Department of Labor Mine Safety and Health 

Administration for establishments in the coal, metal, 

and nonmetal mining industries and data from the U.S. 

Department of Transportation Federal Railroad Administration for railroad incidents. The Survey excludes all 

work-related fatalities, as well as nonfatal work injuries 

and illnesses, to the self-employed; to workers on farms 

with 10 or fewer employees; to private household workers; 

and, nationally, to Federal, State, and local government 

workers. 

Injuries and illnesses logged by employers conform to 

definitions and recordkeeping guidelines set by the Occupational Safety and Health Administration, U.S. Department of Labor (see box). Under these guidelines, nonfatal 

cases are recordable if they are work-related illnesses or injuries that involve lost worktime, medical treatment other 

than first aid, the restriction of work, loss of consciousness, a transfer to another job, or other specific conditions. 

Employers keep counts of injuries separate from counts 

of illnesses. They also identify whether each injury or illness involved any days away from work, days of restricted 

work activity, or both that occurred after the day of injury 

or onset of illness. All employers with 11 or more employees in OSHA-designated high-hazard industries are 

required by OSHA regulation 29 Code of Federal Regulations (CFR) 1904 to maintain logs throughout the year 

and to complete a summary based on the log at the end 

of the year. Other employers also are required to maintain 
Workplace Injuries and Illnesses

22  Monthly Labor Review • August 2008

 

ing program for survey coders and continues to encourage 

survey participants to respond fully and accurately to all 

survey elements. 

There are other data systems that provide estimates of 

occupational injuries and illnesses. An important advantage of SOII is that it is a large system that affords the 

most complete occupational injury and illness counts for 

the Nation and does so consistently across States. While it 

is beyond the scope of this article to discuss other systems 

in detail, a brief summary of some of them is necessary, 

because it is comparisons between SOII and the other systems that provide the basis for the undercount estimates.

Each State has its own workers’ compensation system 

to cover injured and ill workers. The systems vary somewhat but have the same general characteristics. With the 

exception of Texas, all States mandate coverage of nearly 

all private-sector workers. Some States exempt from coverage workers in very small companies, certain agricultural workers, and some other categories of workers.2

 All 

State laws require that employers cover nearly 100 percent 

of an injured or ill worker’s medical expenses and further 

require that workers who are off work longer than a specified “waiting period” be paid cash benefits related to lost 

earnings.3 States differ in the durations of their waiting 

periods, which range from 2 days to 7 days, and also differ 

to a small extent regarding which cases are compensable. 

Recently, for example, a number of States passed legislation requiring that work be a major or predominant cause 

of the disability or legislation eliminating compensation 

for the aggravation of a preexisting condition or for a condition related to the aging process.

Despite the fact that there is a workers’ compensation 

system in each State, national estimates of occupational 

injuries and illnesses are difficult to derive from workers’ 

compensation records because of incomparabilities across 

States. For example, some workers’ compensation databases can provide estimates only of cases for which workers 

are off work for longer than the particular State’s waiting 

period. There are differences in scope between workers’ 

compensation and SOII data with which researchers must 

contend in trying to reconcile estimates between the two 

systems. This issue will be discussed later.

Another data system against which SOII estimates have 

been compared is the National Health Interview Survey 

(NHIS), the principal source of information on the health 

of the civilian noninstitutionalized population of the 

United States and one of the major data collection programs of the National Center for Health Statistics. The 

NHIS is an annual cross-sectional household interview 

survey of about 35,000 households and 87,500 people.4 

logs according to OSHA regulation 29 CFR 1904.42 in the 

event that they are asked to participate in SOII. BLS draws 

a sample of employers for SOII from both OSHA-designated high hazard industries and other industries.

OSHA case recordability criteria

OSHA guidelines for recording cases are codified in 29 CFR

(Code of Federal Regulations) 1904. In general, recordable 

cases include new work-related cases of injuries and illnesses 

or the significant work-related aggravation of preexisting 

non-work-related conditions. Cases are recordable if they 

result in

• death 

• loss of consciousness 

• days away from work 

• restricted work activity or job transfer 

• medical treatment (beyond first aid) 

• significant work-related injuries or illnesses that are 

 diagnosed by a physician or other licensed health care 

 professional, including cancer, chronic irreversible

 disease, a fractured or cracked bone, and a punctured

 eardrum

Cases also are recordable if they meet additional criteria 

for special cases; cases that qualify include those involving 

needlesticks and “sharps” injuries, occupational hearing loss, 

and tuberculosis. The regulations provide definitions of many 

key concepts, explaining how to determine whether a case is 

work related, what is a new case, what is involved in a significant aggravation of a preexisting condition, what is restricted 

work, and so forth.

Occupational injuries, such as sprains, cuts, and fractures, account for the vast majority of all cases that employers log and report to the BLS survey. Occupational illnesses are new cases recognized, diagnosed, and reported 

during the year. Overwhelmingly, those cases which are 

reported are easier to relate directly to workplace activity (for example, contact dermatitis or carpal tunnel syndrome) than are long-latent illnesses, such as cancers.

SOII provides estimates that are based on a scientifically selected sample of establishments, some of which 

represent only themselves but most of which also represent other employers of like industry and workforce 

size that were not chosen in a given survey year. For each 

survey, the sample used is one of many possible samples, 

each of which could have produced different estimates. 

The data also are subject to nonsampling errors that are 

not measured. These errors include the unavailability of 

characteristic data for some cases, mistakes in recording or 

coding the data, and definitional difficulties. To minimize 

nonsampling errors, the Bureau conducts a rigorous train-
Monthly Labor Review • August 2008  23

Among many questions it asks are whether an injury occurred while the individual was working at a paid job, 

what type of medical care was sought, the external cause 

or nature of the injury, what the person was doing when 

the injury occurred, the date and place the injury occurred, 

and whether the person missed days of work.

There are a variety of advantages and disadvantages of 

the NHIS for estimating workplace injuries and illnesses. 

An advantage is that the scope of the survey is broader 

than that of SOII, encompassing all civilian workers, including public-sector workers and the self-employed. Further, Leigh and colleagues argue that economic incentives 

for workers not to report injuries in the NHIS are weak 

to nonexistent. (See discussion of reporting incentives in 

a later section.) However, the sample of injury episodes 

collected by the NHIS is quite small (fewer than 2,000), so 

the NHIS cannot publish the amount of detail that SOII 

can. Further, the NHIS relies on proxy respondents—that 

is, individuals who respond to questions on behalf of other 

household members and who may not be aware of some 

work injuries and illnesses. In addition, workers tend to 

forget less severe injury episodes, so “recall bias” is a problem for injury cases that occurred further away from the 

time of the interview. Beginning with 2004, data were collected on injury episodes occurring within 3 months of 

the interview. However, the National Center for Health 

Statistics tabulates data only for injury cases that occurred 

within 5 weeks of the interview.5 Finally, any comparison 

of NHIS and SOII estimates is complicated by the fact that 

cases in NHIS are not necessarily OSHA recordable (as defined in the box on page 22).

Other data sources used to track workplace injuries and 

illnesses and to compare against SOII include data from 

hospital discharges and emergency room visits. Three of 

the 19 occupational health indicators identified by the 

Council of State and Territorial Epidemiologists (CSTE) 

are based on the National Hospital Discharge Survey.6 As 

noted by CSTE,

[S]tate hospital discharge data are useful for surveillance of 

serious health conditions. While these state data sets do not 

include explicit information about “work-relatedness” of the 

health conditions for which a patient is hospitalized, they do 

include information about the payer for the hospital stay. The 

designation of workers’ compensation as primary payer is a 

good proxy for the work-relatedness of hospitalized injuries.7

Another source of hospital data that can serve to track 

workplace injuries and illnesses is the National Electronic 

Injury Surveillance System (NEISS). Data from this source 

are collected for the National Institute for Occupational 

Safety and Health from a small sample of U.S. hospital 

emergency departments. In each hospital, a staff member 

reads the emergency room charts and identifies work-related cases.

An advantage of using data from hospitals is that all 

workers are potentially in scope, as opposed to the more 

limited scope of SOII. (See later.) However, the cases that 

appear in hospitals are typically more severe than a typical 

OSHA-recordable case. Hospitalizations account for only a 

small percentage of all workplace injuries and illnesses—3 

percent, according to CSTE. Identifying cases by means 

of the payer implies that the cases counted by hospital 

discharge data may or may not be OSHA recordable. Indeed, in the case of the CSTE indicators, these cases would 

be workers’ compensation claims. Similarly, NEISS data 

pertain only to cases treated in emergency departments, 

while the scope of the OSHA-recordable cases counted by 

SOII is both broader and potentially different. Finally, the 

relatively small sample size of the NEISS limits the availability of detailed estimates. All of the data sources just 

described should be viewed as providing estimates that are 

complementary to SOII.

Dimensions of the SOII undercount

Some have viewed SOII with misgivings over its failure to 

count all workplace injuries and illnesses. Their comments 

can be classified into four separate categories: underrecording of illnesses, incomplete scope in the coverage of 

workers, incomplete capture of injury and illness cases 

that are reported in other systems, and unreported cases. 

Underrecording of illnesses. It is well known and acknowledged by BLS that SOII does not capture all occupational 

illnesses. In its press release for SOII, BLS notes that

The survey measures the number of new work-related illness cases that are recognized, diagnosed, and reported 

during the year. Some conditions (for example, long-term 

latent illnesses caused by exposure to carcinogens) often are difficult to relate to the workplace and are not 

adequately recognized and reported. These long-term 

latent illnesses are believed to be understated in the 

survey’s illness measures. In contrast, the overwhelming majority of the reported new illnesses are those that 

are easier to directly relate to workplace activity (for example, contact dermatitis or carpal tunnel syndrome).8

A central problem is that many work-related illnesses 

take years to develop and may be difficult to attribute to 

the workplace. Thus, a recording mechanism based on 

employer records, as is SOII, will generally fail to capture 

these illnesses.
Workplace Injuries and Illnesses

24  Monthly Labor Review • August 2008

SOII scope restrictions. Because of restrictions on the 

scope of the workers covered, SOII does not enumerate all 

nonfatal workplace injuries and illnesses incurred by U.S. 

workers. Specifically, SOII excludes the self-employed; 

farms with fewer than 11 employees; private households; 

Federal Government agencies; and, for national estimates, 

employees in State and local government agencies. SOII 

does collect data on State and local government workers 

in 27 States.

To address this shortcoming, BLS is expanding the collection of data to all government workers. Starting with 

the 2008 survey year, BLS has extended the SOII sample 

to include the 23 States for which State and local government data are not currently collected. Sampled State and 

local government agencies have been asked to record their 

workplace injuries and illnesses on OSHA logs, just as the 

current SOII sample members do. BLS intends to publish 

data for State and local government workers at the national level and for each State. In addition, together with 

OSHA, BLS is exploring ways to collect data for Federal 

agencies. Currently, Federal agencies are required to record their workplace injuries and illnesses on OSHA logs, 

but they are not required to report these data to OSHA.

Collecting data on other workers who are outside the 

scope of SOII (the self-employed, private household workers, and workers on small farms) is problematic, because 

these workers are outside of the scope of the Occupational 

Safety and Health Act of 1970 and therefore are not required to record injuries and illnesses on the OSHA logs 

that form the basis for SOII. In addition, sample frames 

are not available to BLS to capture data on these workers. 

A couple of different approaches might be pursued to collect such data. 

One approach would be to obtain data through a 

household survey such as the NHIS. Workers in the outof-scope groups could be asked about their workplace 

injury and illness experience during a period prior to the 

interview. To obtain estimates consistent with SOII, questions would need to be structured so that the injuries and 

illnesses that are identified are OSHA-recordable cases. 

As with the current NHIS, one potential shortcoming of 

using household interviews is recall bias. Whereas OSHA

instructs employers to record injuries and illnesses on a 

flow basis throughout the year, a survey questionnaire 

would elicit information only for a specified period prior 

to the interview.9 Because workers have been found to 

forget about minor injuries that occurred 6 or more weeks 

prior to the interview,10 the period for which injury and 

illness information would be obtained would need to be 

kept short. This short retrospective period would limit the 

number of cases captured and reduce the reliability of the 

estimates.

Another approach to estimating injury and illness 

rates for the self-employed, household workers, and 

small farms would be to capture data from various other 

sources, including insurance claims, emergency room visits, and hospital discharges. This multisource approach is 

employed by the BLS data program for fatal injuries, the 

Census of Fatal Occupational Injuries (CFOI), though the 

CFOI sources are not the same as those just listed.11 Nonfatal workplace injuries and illnesses that are captured in 

these other systems might differ from OSHA-recordable 

cases. Further, as noted in the previous section, hospital 

data are likely to include only more severe cases. Utilizing 

the aforementioned sources to capture data on nongovernmental workers who are currently outside the scope of 

SOII would be quite resource intensive. 

Absent the collection of data through methods such 

as those just described, some researchers have generated 

estimates for out-of-scope workers. Estimates for some 

groups of workers are obtained from alternative data 

sources that are adjusted to conform to the OSHA-recordability concept underlying SOII. In other cases, estimates 

are produced by extrapolating from the known injury or 

fatality data on other groups of workers.

J. Paul Leigh, James P. Marcin, and Ted R. Miller estimated that in 1999 1.76 million injuries were incurred 

by out-of-scope workers,12 in addition to 5.335 million 

injuries reported in SOII. Thus, Leigh and colleagues estimate that, because of restrictions in scope, SOII did not 

capture 24.8 percent of all workplace injuries and illnesses. 

For some out-of-scope groups (agricultural and Federal 

Government workers), Leigh and colleagues were able 

to obtain other estimates of injuries. For self-employed, 

State and local government, and “other” workers, they 

generated injury and illness estimates by multiplying the 

SOII estimate of injuries by both employment ratios and 

measures of relative risk. (Details appear in their paper.) 

The SOII sample expansion to cover public-sector workers 

will narrow the number of cases incurred by out-of-scope 

workers.

Incomplete SOII capture of injuries and illnesses that are reported in other systems. Another strand of the undercount 

literature argues that SOII fails to capture some cases that 

are within the scope of the survey, but that are captured in 

other work-related injury and illness data systems. At least 

three approaches have been taken to establish whether or 

not SOII and the OSHA logs underlying it are complete: 

OSHA audits of employer recordkeeping, aggregate com-
Monthly Labor Review • August 2008  25

parisons of SOII estimates with estimates generated from 

other data systems, and microlevel matches of cases in 

SOII with cases in other data systems.

OSHA conducts onsite audits of employer injury and 

illness records to verify the overall accuracy of source records and to estimate the extent of employer compliance 

with OSHA recordkeeping requirements. Annually, OSHA

draws a small sample of establishments that have responded to its Data Initiative, and within those establishments, OSHA draws a sample of employees.13 The sample 

is restricted to establishments with 40 or more employees 

in the high-hazard industries (excluding construction) 

covered by the initiative. Further, the establishments must 

be located in States under Federal OSHA jurisdiction or 

in a State Plan State that has decided to participate in 

the initiative. Auditors compare entries on the OSHA logs 

with other records in the establishment.

For calendar year 2004, OSHA found that 95.7 percent of establishments had “accurate” recordkeeping (at 

or above the 95-percent threshold) for total recordable 

injury and illness cases and that 95.3 percent of establishments had “accurate” recordkeeping for cases with days 

away from work, work restrictions, or transfers (DART). 

Among the recordable cases identified by auditors, 10.0 

percent were not recorded, 6.4 percent were DART cases 

recorded as less severe non-DART cases, and 0.9 percent 

were non-DART cases recorded as more severe DART

cases. In 2004, recordkeeping accuracy, according to the 

95-percent criterion, was not statistically significantly different from previous years’ accuracy.

One additional issue uncovered by the OSHA audits is 

overrecording. The audits found instances where employers recorded non-OSHA recordable cases. These were almost exclusively non-DART cases and, as a result, were out 

of the scope of the microdata studies of underreporting to 

be discussed subsequently. Overrecording of these minor 

cases increases the count of total workplace injuries and 

illnesses and partially compensates for the effects of any 

undercounting of more severe cases.

Aggregate studies of the undercount involve comparing 

estimates from SOII with estimates produced from other 

data systems. To the extent that these other data systems 

have different scopes from that of SOII, the estimates need 

to be adjusted to comparable scopes. 

As an example of an aggregate comparison, Leigh and 

colleagues compared SOII estimates with those from the 

National Health Interview Survey (NHIS).14 The SOII estimate of 6.3 million injuries and illnesses in 1994 was 28.2 

percent below the NHIS estimate of 8.8 million injuries 

and illnesses. Leigh and colleagues note that economic incentives for workers not to report in SOII might be weak 

or nonexistent in the NHIS, explaining at least part of the 

estimated undercount.

Not all aggregate comparisons of estimates conclude 

that SOII undercounts injuries and illnesses. Arthur Oleinick and Brian Zaidman compare counts of workers’ 

compensation cases with counts of days-away-from-work 

cases in SOII for Minnesota over the period from 1992 to 

2000.15 For cases lasting 4 or more days away from work—

the cases for which data were available in the Minnesota 

workers’ compensation data set—Oleinick and Zaidman 

conclude that there is 92- to 97-percent concordance between the two estimates of injury and illness counts and 

that the BLS survey has “high sensitivity” for workplace 

injuries with 4 or more days away from work.

There are some limitations of aggregate comparisons. 

Most fundamentally, even if an estimate from another 

data system is close to the SOII estimate, it does not mean 

that underreporting is not present in SOII (or in the other 

system). It is possible that SOII captures some cases that are 

not in the other system, while the other system captures 

some cases that are not in SOII. In such a circumstance, 

there is underreporting in both SOII and the other system. 

Indeed, that is what appears to occur in the microlevel 

studies described shortly. Note, however, that Oleinick 

and Zaidman, who obtained close concordance between 

SOII and workers’ compensation counts, dismissed the 

possibility that offsetting biases resulted in the close concordance that they found.16 

Another limitation of aggregate comparisons is that it 

may be difficult to ensure that the estimates from SOII and 

the other data system are for cases within the same scope. 

The researchers must make careful adjustments to ensure 

scope comparability. The Oleinick and Zaidman study is 

an example in which their adjustments draw the SOII and 

workers’ compensation count estimates together.

To address these purported limitations of aggregate 

comparisons, recent studies have matched individual cases 

in SOII with cases in other systems.17 These studies attempt to restrict the data in SOII and other systems to 

the same scope and then to match cases on a variety of 

characteristics, including those of the worker, employer, 

and case. The studies are able to document the number 

of cases that are in another system but not in SOII, the 

number that are in SOII but not in the other system, and 

the number that are in both SOII and the other system.

Kenneth D. Rosenman and colleagues match case-level 

SOII data to workers’ compensation cases for the State of 

Michigan in 1999, 2000, and 2001.18 Because Michigan 

has a waiting period of 7 days before workers’ compen-
Workplace Injuries and Illnesses

26  Monthly Labor Review • August 2008

sation benefits are paid (hence, only cases that surpass 

the 7-day waiting period are captured in the Michigan 

database), the scope of the data-set comparison was restricted to cases with more than 7 days away from work. 

The researchers estimated that, on average each year from 

1999 to 2001, a total of 79,379 injury and illness cases 

was reported in only SOII, in only workers’ compensation, 

or in both systems. Of these more-than 79,000 cases, SOII 

captured 30,800, or 38.8 percent, whereas workers’ compensation captured 62,264, or 78.4 percent. Focusing on 

specific types of injuries, the researchers found that SOII 

was more likely to capture certain types of injuries that 

are easier to observe and relate to the workplace, such as 

surface and open wounds, burns, and traumatic injuries to 

bones. In contrast, SOII was less likely to capture traumatic 

injuries to muscles, tendons, and the like, which include 

sprains and strains. These injuries are quite frequent both 

in SOII and in workers’ compensation.

Subsequent analysis by Leslie I. Boden and Al Ozonoff 

provides undercount estimates that are considerably 

smaller than those of Rosenman and colleagues.19 Boden 

and Ozonoff match SOII and workers’ compensation data 

from 1998 to 2001 for six States: Minnesota, New Mexico, Oregon, Washington, West Virginia, and Wisconsin. 

The undercount estimates differ by State, but they indicate that on average SOII may be picking up only about 69 

percent of the injuries and illnesses appearing in SOII, in 

workers’ compensation, or in both systems. SOII did best 

at capturing cases in West Virginia (79.4 percent) and 

worst in the State of Washington (55.7 percent). Similarly, the researchers find widely varying estimates of the 

extent to which workers’ compensation captures injuries 

that appear in SOII, workers’ compensation, or both systems—from 72.4 percent in Minnesota to 96.9 percent in 

Washington State.

It is difficult to gauge the reason for the difference in 

the findings of Rosenman and colleagues, on the one hand, 

and Boden and Ozonoff, on the other. The difference may 

be due to differences in the methodologies used, or it may 

be due to State-by-State variation. However, the Rosenman SOII-capture estimate of 38.8 percent is lower than 

the results found by Boden and Ozonoff for any State, 

suggesting that differences in methodology play a role.

Unreported cases. Cases that are unreported in multiple 

data systems constitute another group of undercounted 

cases. In the context of the BLS survey, this means that 

cases not reported in SOII may also not be reported elsewhere. Applying some assumptions, it is possible to estimate the number of such cases by means of a technique 

called capture-recapture. This technique was first applied 

to the estimation of animal populations in the wild, but 

it has been adapted to generate improved estimates in a 

wide variety of situations, such as drug use, homelessness, 

infectious diseases, and occupational injury and illness.20 

Without going into too many technical details,21

capture-recapture uses probability theory and multiple 

overlapping, but incomplete, data sources to make inferences about the size of a partially unobserved population. 

Whereas the most straightforward application of the capture-recapture method uses basic probability theory, more 

sophisticated analyses rely on multivariate models. The 

latter analyses identify all unique cases recorded in at least 

one source and then use log-linear or logistic models to 

estimate the number of cases unrecorded by any source.22

Capture-recapture is a natural extension of the matching 

of data sources described in the previous section.

After matching individual cases in SOII and workers’ 

compensation data for Michigan from 1999 to 2001, 

Rosenman and colleagues used capture-recapture to estimate that although the data sources together included 

a total of 79,379 cases on average each year, an additional 15,654 were not captured in either data system.23

The latter cases bring the annual average total of cases 

to 95,033. Thus, 16.5 percent of cases went unreported. 

Further, when the SOII estimate of 30,800 was compared 

with the total, including unreported cases, Rosenman and 

colleagues estimated that SOII captured only 32.4 percent 

of all cases. 

Boden and Ozonoff applied capture-recapture to the 

data for the six States in their study.24 They found that 

cases unrecorded in either SOII or workers’ compensation 

ranged from 13 percent of all cases in Minnesota and 

New Mexico to 3 percent in Washington State and West 

Virginia. The researchers’ estimate of the total SOII undercount after utilizing capture-recapture was also smaller 

than that of Rosenman and colleagues, ranging from 46 

percent in Washington to 22 percent in West Virginia. 

On average, SOII is estimated to capture about 60 percent 

of all cases across the six States. As previously mentioned, 

capture-recapture has been used for a variety of purposes. 

In an interesting non-U.S. example, Anton W. Moll Van 

Charante and Paul G. Mulder found that employers reported only 35.6 percent of injuries to the government in 

the Netherlands.25

Capture-recapture is a sophisticated technique for 

making inferences about unreported cases. However, the 

methodology does rely on some assumptions to generate 

results. One important assumption, termed “source independence,” is that the recording of cases in one system is 
Monthly Labor Review • August 2008  27

independent of the recording of cases in another system. 

In fact, sources could be positively or negatively source 

dependent, meaning that a case recorded in one system 

is, respectively, more likely or less likely to be recorded 

in another system. For a variety of reasons, Boden and 

Ozonoff expect that SOII and workers’ compensation are 

positively source dependent. Some of these reasons are 

that the same person might record a case in both systems; 

if a worker does not report a case, it is not likely to be recorded in either system; and if an employer does not think 

a case is compensable, then he or she might erroneously 

believe that it also is not OSHA recordable.

If two sources are positively source dependent, then the 

estimate of the number of cases not captured in either system is biased downward; that is, underreporting is greater 

than when the number of cases is estimated under the 

assumption of independence. Without data from a third 

source or without additional assumptions, it is not possible to estimate the extent of source dependence. Still, 

Boden and Ozonoff conduct a sensitivity analysis by estimating the undercount under a couple of positive dependence scenarios.26 Assuming different values for the 

odds ratio that a case is reported in SOII, given that it is 

reported in workers’ compensation,27 they show that the 

estimated coverage of both SOII and workers’ compensation drops with positive source dependence—sometimes 

substantially. However, they concede that they do not 

know what the correct odds ratio is (although they believe 

it is greater than one), leaving the source dependence issue 

unresolved.

Reasons for the undercount findings

The previous two sections summarize research which concludes that SOII misses some cases that are recorded in 

workers’ compensation and other cases that do not appear 

in workers’ compensation. Although willful underreporting might be one explanation for these findings, there are 

a variety of other explanations as well:

SOII and workers’ compensation are independent 

systems, so a case might be recordable in one system 

but not the other.

Employers might have legitimate doubts about the 

recordability of some cases, particularly those being 

contested in the workers’ compensation program.

An aspect of SOII—its timeliness—may contribute 

in a modest way to the undercount, particularly when 

•

•

•

updates to logs occur after data collection.

The undercount research studies might be unable to 

overcome some methodological challenges that increase the estimated undercount.

These hypotheses are discussed next.

Because SOII and workers’ compensation are technically 

independent systems for recording injuries and illnesses, 

there may be valid reasons that a case could appear in one 

system but not the other. For example, in the matching 

work previously described, cases with days away from 

work are matched. In SOII, a case with days away from 

work must involve at least 1 day away from work following the day of the incident. However, a workers’ compensation insurer might capture a compensable case that involves permanent disability without days away from work 

or with only partial days away from work. As a result, as 

Eleni Messiou and Brian Zaidman note, some workers’ 

compensation claims may not include enough days away 

from work to be classified as a days-away-from-work 

case in SOII.

28 Another area of concern is the treatment 

of multiple spells out of work associated with the same 

injury (the question being whether a recurring injury is 

treated as a new injury each time it recurs).29

Messiou and Zaidman,30 as well as Nicole Nestoriak 

and Brooks Pierce,31 point out that the timing of the compilation of different sources of occupational safety and 

health information may partially explain why some workers’ compensation cases do not match to SOII cases. SOII is 

fielded soon after the end of the reference year in order to 

correspond to the time when OSHA requires the summary 

of injuries and illnesses to be posted in the workplace. In 

contrast, workers’ compensation records are continuously 

updated, and the extracts from the workers’ compensation 

database that are used for matching research are often 

drawn long after the end of the reference year. Some cases 

are noticed or reported with a lag, causing them not to get 

entered into the OSHA log before SOII is administered. 

Also, although employers are instructed to update their 

OSHA logs when new information is obtained, they may 

forget to do so or might do it after they respond to SOII. 

Thus, the workers’ compensation information may be 

more up to date and more inclusive than the information 

available for SOII. This difference complicates the matching of cases and leads to nonmatches. 

Consistent with the previous hypothesis, a reanalysis of 

Boden and Ozonoff ’s Wisconsin data by BLS found that 

SOII misses relatively more cases late in the survey year 

and also misses a large fraction of cases that are entered 

•
Workplace Injuries and Illnesses

28  Monthly Labor Review • August 2008

into the workers’ compensation database after the end of 

the survey year.32 Cases that occur late in the survey year 

are less likely to have been entered into or updated in the 

log by the time the survey is administered. However, the 

fact that the yearend effect is apparent for December but 

not for November or earlier suggests that whatever effect is operating is a relatively short-window effect; consequently, it can explain relatively little of the year-round 

SOII undercount. Cases that are not entered into the 

workers’ compensation database until the following year 

may not be recognized in time to be entered into OSHA

logs and captured in SOII.

The issue of timing also may affect the matching of 

contested cases—that is, those cases which the employer 

does not recognize either as existing or as being work related. It is reasonable to expect that an employer might 

not record such a case on OSHA logs until the status of 

the workers’ compensation case is resolved (if ever). Such 

a resolution might occur long after the data in SOII have 

been collected. Thus, a resolved contested case might appear in the workers’ compensation files but not in the SOII

files being matched.

The quality of the undercount estimates depends critically upon how well the SOII cases are matched to workers’ compensation cases and how well the researchers 

can adjust for differences between the SOII and workers’ 

compensation data. Missed matches are counted as undercounts in both data sets. There are aspects of SOII that 

create challenges for matching cases and for estimating an 

undercount with respect to workers’ compensation. 

Cases match only if the two lists of cases cover the 

same populations of injuries and illnesses (that is, if the 

lists have the same scope). If lists are not consistent, then 

a case might appear on one list but not the other. Some 

inconsistencies between lists can be corrected directly 

through exclusions. For example, an injury resulting in 

few days away from work may be OSHA-recordable but 

not compensable according to workers’ compensation. It 

is important to recognize that the fields used for exclusion 

may be error prone and that any errors incurred can effectively lead to mismatch issues. For example, if a particular 

case is recorded as having 6 days away from work in SOII 

but has 8 days away according to workers’ compensation, 

then excluding the case from SOII on the basis of a 7-day 

waiting period exclusion will make it appear as if SOII did 

not capture that case while workers’ compensation did.33 

Mismatch bias depends on the matching technology used 

by the researcher, on the error rates in SOII data elements, 

on error rates in the workers’ compensation data elements, 

and on whether the error rates in the workers’ compensation and SOII data elements are positively correlated with 

each other.

In addition, there are aspects of SOII that create additional difficulties. SOII is an establishment survey in 

which only certain establishments are sampled. Workers’ 

compensation reports cover all compensable cases and 

are frequently based on company records. In the case of a 

company with multiple establishments, it is possible that 

only certain establishments of that company are in SOII, 

whereas the workers’ compensation data contain data on 

all of the company’s establishments. Researchers conducting SOII-to-workers’-compensation matches have found 

it difficult to identify the establishment locations for 

workers’ compensation cases; this in turn makes it difficult 

to determine whether a particular workers’ compensation 

case should have a corresponding case in SOII. Boden and 

Ozonoff ’s solution to this problem is to use a universe 

file of establishments (the Quarterly Census of Employment and Wages) to determine the fraction of the total 

employment at the affiliated firm covered by the sampled 

BLS establishments. This fraction is then used to lower 

the weight applied to the workers’ compensation unlinked 

cases (because these cases may be from an establishment 

not sampled for SOII). Although this solution makes good 

use of the available information, it does introduce additional nonsampling error.

Subsequent BLS analysis of Boden’s Wisconsin sample 

abstracted from the multiestablishment problem by analyzing only matches for single-establishment companies. 

SOII misses relatively fewer cases in single-establishment 

firms, suggesting that it may be difficult to overcome 

matching problems for multiestablishment companies. 

However, it is also possible that establishments in singleestablishment companies differ from establishments in 

multiestablishment companies in characteristics (for example, establishment size) that are associated with the 

likelihood of matching cases between SOII and workers’ 

compensation. Future multivariate analysis may help determine the relative importance of factors responsible for 

the single-establishment result.

Another aspect of SOII that may cause a difficulty 

in matching is the fact that large establishments report 

only a sample of their cases. Specifically, a small number of large establishments are told to report cases that 

occur only during a particular timespan in the survey 

year. Inconsistencies between the date of onset of injury 

or illness for a SOII case and that of the corresponding 

workers’ compensation case may lead to mismatches and 

measured underreporting both in SOII and in workers’ 

compensation. For example, suppose that, according to 
Monthly Labor Review • August 2008  29

workers’ compensation, a particular case occurs during 

the reporting timeframe for an establishment that subsamples cases in SOII. Suppose, however, that the case 

is recorded on the OSHA log as occurring outside the 

subsampling timeframe. Because it is recorded in this 

way, the case will not be reported to SOII, and it will appear that there is a SOII undercount. Similarly, if a case 

appears to occur outside the subsampling timeframe according to workers’ compensation, but falls within that 

timeframe when recorded on the OSHA log, then the 

case will be reported to SOII and it will appear that there 

is a workers’ compensation undercount.

There is some empirical evidence of the impact of 

case subsampling on the undercount estimates. Determining date of onset may be particularly difficult for 

some types of cases, such as carpal tunnel syndrome. 

Indeed, consistent with this explanation for potential 

underreporting was Boden and Ozonoff ’s finding that 

carpal tunnel syndrome cases had a higher incidence of 

underreporting than other cases. (Note, however, that 

differences in date of onset may make it difficult to 

match a case even if it appears in both systems.) Further, Nestoriak and Pierce found that SOII captures a 

slightly lower percentage of cases where subsampling 

occurs.34 However, they also found that undercounting 

was greater, and that case subsampling arises, in larger 

establishments. Disentangling the various effects will 

require multivariate analysis; BLS plans to conduct such 

an analysis in the future.

This discussion points out that there are a number of 

features of workplace safety and health data that make it 

difficult to match cases. Although false positive matches 

may also occur, it seems likely that the preponderance of 

mismatches are false negatives—that is, failures to match 

cases that should be matched. Thus, matching errors seem 

to be biased in favor of an undercount.

The empirical work of Rosenman, Boden, and others utilizing capture-recapture methodology finds that 

a large number of cases go unreported in multiple data 

systems. Lenore S. Azaroff, Charles Levenstein, and 

David H. Wegman detail a variety of “filters” that may 

cause this to occur. Azaroff and colleagues hypothesize 

that workers who report health problems to supervisors may risk (or fear) a variety of adverse outcomes.35

Supporting this hypothesis, Tim Morse, Laura Punnett, 

Nicholas Warren, Charles Dillon, and Andrew Warren found evidence that workers at unionized facilities 

were more likely than workers at nonunionized facilities 

to file workers’ compensation claims for musculoskeletal disorders, despite rates of such disorders that were 

comparable between the two groups of workers. These 

researchers hypothesized that unions protect workers reporting musculoskeletal disorders.36 Other filters 

identified by Azaroff as discouraging workers from reporting include safety incentive programs that reward 

teams of workers who do not sustain and report injuries 

and the failure of workers (and employers) to perceive 

the work-relatedness of a particular health condition. 

For all these reasons, a workplace injury or illness could 

go unreported, and thus unrecorded, in any occupational 

injury and illness tracking system.

Even when workers do report injuries, argue Azaroff 

and colleagues, there may be incentives working against 

taking time off or reporting a case as work related. 

Among such incentives are the uncertainty of receiving 

workers’ compensation benefits if a claim is contested, 

the waiting periods before partial wage-replacement 

workers’ compensation benefits are paid, worker ignorance about workers’ compensation, and employer and 

employee incentives that favor the use of health insurance in place of workers’ compensation. Rosenman and 

colleagues,37 as well as Jeff Biddle and Karen Roberts,38

found that many Michigan workers who were diagnosed 

with work-related repeated-trauma injuries did not file 

workers’ compensation claims. Factors that raised the 

probability of filing included the severity of the condition and the generosity of wage loss benefits. Thus, in 

some situations where an occupational injury or illness 

has arisen, either the worker does not report it as such, 

does not take time off work, or does not file a workers’ 

compensation claim. These cases will not appear in SOII

or workers’ compensation.

Although the foregoing analysis has largely discussed 

employee incentives not to report injuries and illnesses, 

employers also may have underreporting incentives. 

Increasingly, injury and illness rates are used as an 

evaluation criterion in competitions for contract work. 

Lower rates improve a bidder’s chances of winning a 

contract. In addition, it is alleged that some employers underreport to avoid OSHA scrutiny, because OSHA

targets employers with higher rates for inspection.39 It 

is important to note that, although commentators have 

advanced hypotheses regarding reporting disincentives 

faced by employers and workers, little research on the 

magnitudes of the impacts of these various disincentives 

on underreporting has been conducted.

Bureau of Labor Statistics activities

BLS has initiated a variety of activities aimed at under-
Workplace Injuries and Illnesses

30  Monthly Labor Review • August 2008

standing and, to the extent possible, addressing the undercount issue: 

Expansion of SOII’s scope. As mentioned earlier, BLS

is expanding the scope of SOII to include State and 

local government workers in all States. BLS also is exploring with OSHA ways to capture data for Federal 

Government workers. These expansions of the survey 

encompass all public sector workers for the first time, 

including those in high-hazard occupations, such as 

police officers, fire-fighters, and public health workers.

Collecting data for the self-employed and household workers requires a different data collection 

approach from the one utilized by SOII, because 

these workers are not covered by the Occupational 

Safety and Health Act and are not included in the 

SOII establishment-based sample frame. BLS has 

no plans to expand SOII to cover these workers, but 

it will work with other groups in exploring the use 

of alternate data systems that cover these workers.

A quality assurance recontact survey. In 2007, BLS

conducted a quality assurance recontact survey which 

indicated that BLS survey processes were not responsible for an undercount. BLS recontacted a sample of 

3,600 establishments that participated in the 2006 

survey and asked them to submit their OSHA logs. 

The data on the logs were compared with data from 

SOII. There was no systematic evidence that SOII

had undercounted cases recorded on the OSHA logs.

Examination and extension of undercount 

research. BLS is currently studying matched SOII

data and workers’ compensation data for Wisconsin that were previously assembled and analyzed by 

Boden and Ozonoff.40 After that analysis concludes, 

BLS will analyze data for Kentucky and Maine. The 

goal is to determine whether certain types of cases 

and respondents display greater evidence of underreporting and to determine what factors other than 

willful underreporting might be responsible for any 

undercount finding. These factors include legitimate 

differences among different data systems and methodological aspects of undercount research that might 

provide biased estimates of the SOII undercount.

Employer interviews. In 2008, BLS is interviewing 

a small number of SOII respondents to learn the decisions they make about reporting cases to workers’ 

compensation and reporting them on the OSHA log. 

1.

2.

3.

4.

The purpose is to understand situations where workers’ compensation cases are not recorded on OSHA logs 

and vice versa. The interviews are being conducted by 

a BLS cognitive survey methodologist. At the 2009 

budget request level, BLS plans to expand the number 

of these interviews conducted in Fiscal Year 2009.

Piloting the estimation of workplace injuries and illnesses from multiple sources. The work of Rosenman and colleagues, Boden and Ozonoff, and others 

suggests that no single data source can measure the 

total burden of workplace injuries and illnesses. Using multiple data sources can improve completeness 

of coverage by including workers and cases that are 

outside the scope of any particular data source and 

by covering cases that, for a variety of possible reasons, do not appear in a particular data set. This, in 

fact, is the rationale for the BLS Census of Fatal Occupational Injuries. BLS hopes to work in partnership with the National Institute for Occupational 

Safety and Health, the Council of State and Territorial Epidemiologists, and some States to pilot the 

estimation of workplace injuries and illnesses using 

multiple data sources. This pilot would focus on two 

types of injury or illness—one acute, such as amputations, and one with a more gradual onset, such 

as carpal tunnel syndrome—each studied in a small 

number of States. Employer- and non-employerbased data sources might be explored. Such a pilot 

would provide information on the feasibility and 

cost of implementing a multiple-source data system 

for measuring the total burden of workplace injuries 

and illnesses in the United States.

SOII IS DESIGNED TO MEASURE THE NUMBER of 

OSHA-recordable cases of workplace injuries and illnesses. 

It covers most, but not all, sectors of the U.S. economy. 

This means that SOII does not capture some workplace 

injuries and illnesses that appear in other data systems, 

because of differences in the scope of cases captured and 

sectors covered. SOII also may be limited in completeness 

by incentives that affect worker and employer reporting 

of workplace injuries and illnesses. Further, with an employer-based system for counting workplace injuries and 

illnesses such as SOII, it is difficult to measure long-latent 

occupational illnesses. For all of these reasons, SOII does 

not measure the total burden of workplace injuries and 

illnesses.

However, SOII has advantages over other data systems. 

It efficiently and quickly produces detailed estimates that 

5.
Monthly Labor Review • August 2008  31

are consistent in definition across all States and industries. For cases with days away from work, it provides rich 

information about the occupation and demographics of 

injured or ill workers and about case characteristics such 

as the number of days away from work, the nature of 

the case (for example, a fracture), the body part affected, 

the event (a fall, for instance), the source (the floor, for 

example) and the timing of the incident. In comparison 

with SOII, many other data systems are not consistent 

across States (workers’ compensation is the prime example); cannot produce detailed estimates by State, industry, and case characteristics (NHIS is an example); do not 

exist for all States; or are very expensive to collect. These 

other systems also may have major scope limitations (for 

example, they measure only hospitalizations) or may be 

affected by various reporting incentives.

Some recent studies conclude that both SOII and 

other data systems undercount cases of workplace injuries and illnesses. Explanations other than willful underreporting—such as differences in the cases captured 

by various data systems and methodological aspects of 

the undercount research—may account for this finding. 

Some have argued that the gold standard for producing 

estimates of the total burden of workplace injuries and 

illnesses is a multiple data source system. Indeed, BLS has 

implemented such an approach in collecting workplace 

fatal injury data. However, in 2006, there were 4.1 million OSHA-recordable nonfatal workplace injuries and 

illnesses in private industry according to SOII, in comparison with 5,840 workplace injury fatalities counted by 

CFOI in all sectors of the U.S. economy. The vastly greater 

number of nonfatal injuries and illnesses suggests that 

it would be quite costly to implement a multiple data 

source system uniformly across all States for all nonfatal 

occupational injuries and illnesses. However, BLS hopes 

to partner with States and other organizations in a pilot 

to assess the cost and feasibility of a multiple data source 

approach for nonfatal cases.

Within the constraints of its mission as a statistical 

agency, BLS will continue to work to ensure that SOII 

accurately measures in-scope workplace injuries and illnesses. As described in this article, BLS will undertake 

and publish additional research designed to understand 

and explain differences between its estimates and those 

of other systems. Finally, where feasible, BLS will expand 

SOII’s coverage of the economy to give a more complete 

picture of the total burden of workplace injuries and illnesses.

Notes

1 Under this Federal/State program, participating States perform many survey functions, such as sample refinement and data collection, coding, and keying 

information into a database. Participating States obtain their own estimates and 

select the industries for which they get these estimates. States match Federal 

funding for their data collection work in a 50–50 cost-sharing arrangement. For 

the 2007 survey year, 42 States and the District of Columbia participated in the 

SOII. BLS regional office staff collect data for nonparticipating States, and those 

data are used to produce national, but not State, estimates. 

2

 Ishita Sengupta, Virginia Reno, and John F. Burton, Jr., Workers’ Compensation: Benefits, Coverage and Costs, 2005 (Washington, DC, National Academy of 

Social Insurance, 2007).

3 States also have varying “retroactive periods.” Workers who are off work 

longer than these retroactive periods are paid income benefits for the waiting 

period.

4 National Health Interview Survey, National Center for Health Statistics, 

2008. Documentation available at www.cdc.gov/nchs/about/major/nhis/hisdesc.htm (visited July 17, 2008).

5 Ibid.

6

 The National Hospital Discharge Survey collects data from a sample of 

approximately 270,000 inpatient records acquired from a national sample of 

about 500 hospitals. For more information, see www.cdc.gov/nchs/about/major/hdasd/nhdsdes.htm (visited July 16, 2008). 

7

 Quoted from www.cste.org/dnn/ProgramsandActivities/OccupationalHealth/OccupationalHealthIndicators/Indicator2/tabid/97/Default.

aspx (visited July 16, 2008).

8 Workplace Injuries and Illnesses in 2006, News Release number USDL 07–

1562, (Bureau of Labor Statistics, 2007).

9 OSHA instructs employers to record cases within 7 calendar days of learning that a recordable work-related injury or illness has occurred.

10 M. Warner, N. Schenker, M. A. Heinen, and L.A. Fingerhut, “The effects 

of recall on reporting injury and poisoning episodes in the National Health 

Interview Survey,” Injury Prevention, October 2005, pp. 282–87.

11 CFOI uses a variety of data sources, including death certificates, workers’ compensation reports, and Federal and State agency administrative reports. 

CFOI does not use data from private health insurance companies or hospital 

visits.

12 J. Paul Leigh, James P. Marcin, and Ted R. Miller, “An estimate of the U.S. 

Government’s undercount of nonfatal occupational injuries,” Journal of Occupational and Environmental Medicine, January 2004, pp. 10–18.

13 Through its OSHA Data Initiative survey, OSHA collects injury and illness data from larger establishments in historically high-rate industries. These 

data are used to target inspections under OSHA’s Site-Specific Targeting (SST) 

program.

14 Leigh and others, “An estimate of the U.S. Government’s undercount.”

15 Arthur Oleinick and Brian Zaidman, “Methodological Issues in the Use 

of Workers’ Compensation Databases for the Study of Work Injuries with Days 

Away from Work. I. Sensitivity of Case Ascertainment,” American Journal of 

Industrial Medicine, March 2004, pp. 260–74.

16 Ibid., p. 268.

17 All matching research involving SOII microdata was conducted at BLS 

under Memoranda of Understanding between BLS and the researchers’ institutions, permitting access to SOII data only for the purpose of conducting the sta-
Workplace Injuries and Illnesses

32  Monthly Labor Review • August 2008

tistical matching studies. All analyses and tabulations that were removed from 

BLS were screened for confidentiality. All data sets containing confidential BLS

information remained at BLS.

18 Kenneth D. Rosenman, Alice Kalush, Mary Jo Reilly, Joseph C. Gardiner, 

Mathew Reeves, and Zhewui Luo, “How Much Work-Related Injury and Illness is Missed by the Current National Surveillance System?” Journal of Occupational and Environmental Medicine, April 2006, pp. 357–65.

19 Leslie I. Boden and Al Ozonoff, “Capture-Recapture Estimates of Nonfatal Workplace Injuries and Illnesses,” Annals of Epidemiology, June 2008, pp. 

500–06. 

20 Ibid.

21 For more technical information, see Ernest B. Hook and Ronald R. Regal, 

“Capture-recapture methods in epidemiology: methods and limitations,” Epidemiologic Reviews, 1995, pp. 243–64.

22 Boden and Ozonoff, “Capture-Recapture Estimates.”

23 Rosenman and others, “How Much Work-Related Injury and Illness is 

Missed.”

24 Ibid.

25 Anton W. Moll Van Charante and Paul G. Mulder, “Reporting of Industrial Accidents in the Netherlands,” American Journal of Epidemiology, July 15, 

1998, pp. 182–190.

26 Boden and Ozonoff, “Capture-Recapture Estimates.”

27 The odds ratio has a value of 1 if the two sources are independent. With 

positive source dependence, the odds ratio is greater than 1.

28 Eleni Messiou and Brian Zaidman, “Comparing Workers’ Compensation 

Claims and OSHA Data Initiative Cases.” Mimeo, (Minnesota Department of 

Labor and Industry, 2005).

29 An OSHA recordkeeping change in 2002 instructed employers not to 

count recurrent symptoms of the same injury or illness.

30 Messiou and Zaidman, “Comparing Workers’ Compensation Claims.”

31 Nicole Nestoriak and Brooks Pierce. Preliminary Report on the Boden Undercount Study (Bureau of Labor Statistics, 2008).

32 Ibid.

33 One possible source of error in the count of days away from work on the 

OSHA log arises from the fact that employers are required to record the number of days lost within 7 calendar days. Anecdotal evidence suggests that some 

employers may record the actual day count missed up to the point of recording, 

rather than estimating the number of days missed as they are instructed initially 

to do. Employers also are instructed to update the day count when the actual 

number of days is known.

34 Nestoriak and Pierce. Preliminary Report.

35 Lenore S. Azaroff, Charles Levenstein, and David H. Wegman, “Occupational injury and illness surveillance: Conceptual filters explain underreporting,” 

American Journal of Public Health, September 2002, pp. 1421–29.

36 Tim Morse, Laura Punnett, Nicholas Warren, Charles Dillon, and Andrew Warren, “The Relationship of Unions to Prevalence and Claim Filing for 

Work-Related Upper-Extremity Musculoskeletal Disorders,” American Journal 

of Industrial Medicine, July 2003, pp. 83–93.

37 K. D. Rosenman, J. C. Gardiner, J. Wang, J. Biddle, A. Hogan, M.J. Reilly, 

K. Roberts, and E. Welch, “Why Most Workers with Occupational Repetitive 

Trauma Do Not File for Workers’ Compensation,” Journal of Occupational and 

Environmental Medicine, January 2000, pp. 25–34.

38 Jeff Biddle and Karen Roberts, “Claiming Behavior in Workers’ Compensation,” The Journal of Risk and Insurance, December 2003, pp. 759–80.

39 Leigh, Marcin, and Miller, “An estimate of the U.S. Government’s undercount.” 

40 Boden and Ozonoff, “Capture-Recapture Estimates.”