Statistics: Reporting Systems and Methods

Even though most of the fundamental problems with official crime statistics had been identified before the end of the nineteenth century, including the major problem of the dark figure of unknown crime, it was not until the mid-twentieth century that systematic attempts to unravel some of the mysteries of official statistics were initiated. Turning to data sources outside of the official agencies of criminal justice, unofficial crime statistics were generated in order to explore the dark figure of crime that did not become known to the police, to create measures of crime that were independent of the official registrars of crime and crime control, and to address more general validity and reliability issues in the measurement of crime.

There are two categories of unofficial data sources: social-science and private-agency records. The first of these is much more important and useful. Among the social-science sources, there are two major, significant measures, both utilizing survey methods. The first is self-reports of criminal involvement, which were initially used in the 1940s to "expose" the amount of hidden crime. The second is surveys of victimization, the most recent and probably the most important and influential of the unofficial crime statistics. Victimization surveys were initiated in the mid-1960s to "illuminate"–that is, to specify rather than simply to expose—the dark figure and to depict crime from the victim's perspective. There are also two minor, much less significant sources of social-science data: observation studies of crime or criminal justice, and experiments on deviant behavior. Among the sources of private-agency records are those compiled by firms or industries to monitor property losses, injuries, or claims; by private security organizations; and by national trade associations. The focus here will be on the social-science sources of unofficial crime statistics, particularly victimization and self-report surveys.

Victimization surveys. Recognizing the inadequacies of official measures of crime, particularly the apparently substantial volume of crime and victimization that remains unknown to, and therefore unacted upon by, criminal justice authorities, the President's Commission on Law Enforcement and Administration of Justice initiated relatively small-scale pilot victimization surveys in 1966. One was conducted in Washington, D.C. A sample of police precincts with medium and high crime rates was selected, within which interviews were conducted with residents. Respondents were asked whether in the past year they had been a victim of any of the index crimes and of assorted nonindex crimes. Another surveyed business establishments in the same precincts in Washington, D.C., as well as businesses and residents in a sample of high-crime-rate precincts in Boston and Chicago. The instruments and procedures used in the first pilot survey were modified and used to interview residents in the second study. Owners and managers of businesses were asked whether their organization had been victimized by burglary, robbery, or shoplifting during the past year. The third pilot survey was a national poll of a representative sample of ten thousand households. Again, respondents were interviewed and asked whether they or anyone living with them had been a victim of index and nonindex crimes during the past year. They were also asked their opinions regarding the police and the perceived personal risk of being victimized.

The pilot studies verified empirically what criminologists had known intuitively since the early nineteenth century—that official crime statistics, even of crimes known to the police, underestimate the actual amount of crime. However, these victimization studies showed that the dark figure of hidden crime was substantially larger than expected. In the Washington, D.C., study, the ratio of reported total victim incidents to crimes known to the police was more than twenty to one (Biderman). This dramatic ratio of hidden victimizations to reported crimes was replicated among the individual victims in the Boston and Chicago study (Reiss) and in the national pilot survey, which showed that about half of the victimizations were not reported to the police (Ennis). The survey of business establishments discovered the inadequacy of business records as measures of crime, showed higher rates of victimization than police records indicated, and verified the valid reporting of business victimization by respondents (Reiss). These studies also demonstrated that the discrepancy between the number of victimizations and of crimes reported to the police varies importantly by the type of offense and by the victim's belief that reporting a crime will have consequences. In general, the more serious the crime, the more likely a victim is to report it to the police; minor property crimes are reported least frequently. As a result of the startling findings of these pilot victimization surveys and of the subsequent recommendations of the President's Commission, an annual national victimization was initiated in the National Crime Victim Survey (NCVS).

In 1972 the United States became one of the few countries to carry out annual national victimization surveys. The NCVS is sponsored by the Bureau of Justice Statistics (within the United States Department of Justice) and is conducted by the Bureau of the Census. Its primary purpose is to "measure the annual change in crime incidents for a limited set of major crimes and to characterize some of the socioeconomic aspects of both the reported events and their victims" (Penick and Owens, p. 220). In short, the survey is designed to measure the amount, distribution, and trends of victimization and, therefore, of crime.

The survey covers a representative national sample of approximately sixty thousand households, and through 1976 it included a probability sample of some fifteen thousand business establishments. Within each household, all occupants fourteen years of age or older are interviewed, and information on twelve- and thirteen-yearold occupants is gathered from an older occupant. Interviews are conducted every six months for three years, after which a different household is interviewed, in a constant process of sample entry and replacement.

The crimes measured in the NCVS are personal crimes (rape, robbery, assault, and theft), household crimes (burglary, larceny, and motor-vehicle theft), and business crimes (burglary and robbery). These crimes were selected intentionally for their similarity to the index crimes of the UCR in order to permit important comparisons between the two data sets. The only two index crimes missing are murder, for which no victim can report victimization, and arson, the ostensible victim of which is often the perpetrator.

The statistics on victimization generated by the NCVS provide an extremely important additional perspective on crime in the United States. Ever since they were first published, the survey's reports have forced a revision in thinking about crime. For example, a report on victimization in eight American cities, using data from the very first surveys, provided striking confirmation of the magnitude of the underreporting and nonreporting problem identified in the pilot projects. Comparing the rates of victimization and crimes known to the police, the victimization data showed fifteen times as much assault, nine times more robbery, seven times the amount of rape, and, surprisingly, five times more motor-vehicle theft than reported in the UCR for the same period (U.S. Department of Justice).

Some of the discrepancy in the two rates can be accounted for by the practices of the police—not viewing a reported offense as a crime, failing to react, and not counting and recording it. But since the time of the pilot research it has been clear that the major reason for the discrepancy is the reporting practices of victims: the pilot national survey reported that approximately 50 percent of victimizations are not reported to the police (Ennis). An analysis of preliminary data from the first NCVS in 1973 concluded that nonreporting by victims accounted for much more of the difference between victimization and official crime rates than did nonrecording by the police. Almost three-fourths (72 percent) of the crime incidents are not reported to the police, ranging from a nonreporting rate of 32 percent for motor-vehicle theft to a rate of 82 percent for larceny (Skogan).

The primary reasons for citizen hesitancy to report crime to the police are relatively clear—the victim does not believe that reporting will make any difference (35 percent) or that the crime is not serious enough to bring to the attention of authorities (31 percent) (U.S. Bureau of the Census). The less serious crimes, particularly minor property crimes, are less often reported to the police, and the more serious ones are reported more often. Paradoxically, some of the more serious personal crimes, including aggravated assault or rape, are not reported because a personal relationship between victim and perpetrator is being protected or is the source of potential retribution and further harm (Hindelang, Gottfredson, and Garofalo). Another crime, arson, presents the problems of potential overreporting and of distinguishing between victim and perpetrator, since collecting insurance money is often the motive in burning one's own property.

The NCVS does not merely provide another national index of crime, a view of crime from the perspective of the victim, and illumination of the dark figure of hidden crime. It has also contributed to a better understanding of crime in the United States, forcing scholars and criminal justice professionals alike to question many basic assumptions about crime. Perhaps most perplexing are the implications of the victimization trend data. From 1973 to the 1990s, the overall victimization rate remained relatively stable from year to year, whereas the UCR showed a more inconsistent and upward trend. It was not until the observed decline in crime from about 1992 until 2001, that the UCR and NCVS both showed the same trend, due perhaps to refinements in both systems. However, there are a number of possible interpretations for the differences, centering on the relative strengths and weaknesses of official records of crimes known to the police, as compared to unofficial victim reports.

In general, victimization surveys have the same problems and threats to validity and reliability as any other social-science survey, as well as some that are specific to the NCVS. Ironically, there is a "double dark figure" of hidden crime—crime that is not reported to interviewers in victimization surveys designed to uncover crimes not reported to the police! Such incomplete reporting of victimization means that victimization surveys, like official data sources, also underestimate the true amount of crime. Of course, this suggests that the discrepancy between the crime rate estimates of the NCVS and of the UCR is even larger than reports indicate.

A number of factors contribute to this doubly dark figure of unreported victims. One of the most difficult problems in victimization surveys is to anchor the reported crime within the six-month response frame. A respondent not only has to remember the crime incident, but must also specify when it took place during the past six months. Memory may be faulty the longer the period of time between the crime and interview; the more likely is memory to fail a respondent who either forgets an incident completely or does not remember some important details about the victimization. The less serious and more common offenses are less worth remembering because of their more trivial nature and ephemeral consequences. The concern and tolerance levels of victims may also affect their recollection of crime incidents. Moreover, telescoping may take place: the victimization may be moved forward or backward in time, from one period to another. A victim knows that a crime took place but cannot recall precisely when. Another source of inaccurate and inconsistent responses is deceit. Some respondents may simply lie, or at least shade their answers. There are many reasons for deceit, including embarrassment, social desirability (wish to make a socially desirable response), interviewer-respondent mistrust, personal aggrandizement, attempts to protect the perpetrator, disinterest, and lack of motivation. Memory decay and telescoping are neither intentional nor manipulative, and are therefore more random in their effects on responses. They are likely to contribute to the underestimation of victimization. However, deceit is intentional and manipulative, and it is more likely to characterize the responses of those who have a reason to hide or reveal something. The effects on victimization estimates are more unpredictable because deceit may lead to underreporting among respondents but to overreporting among others. One can assess the extent of underreporting through devices such as a "reverse record check," by means of which respondents who have reported crimes to the police are included in the survey sample (Turner; Hindelang, Hirschi, and Weis, 1981). Comparing a respondent's crime incidents reported in the victimization interview with those reported to the police provides a measure of underreporting. A problem, though, is that underreporting can be validated more easily than overreporting. One "underreports" crimes that actually took place. For every official crime known to the police of a particular offense category, one can be relatively certain of underreporting if no victimization is reported for that offense category. If more victimizations are reported for an offense category than are known to the police, one cannot know whether the respondent is overreporting. A person may "overreport" crimes that never took place—they cannot be known, verified, or validated.

One of the strengths of the NCVS, namely, that the crimes included in the questionnaire are F.B.I. index crimes, is also a problem. In addition to the fact that two of the index crimes (murder and arson) are not included, many other important crimes are not measured in the victimization surveys. Obviously, the whole array of crimes without victims are excluded, as well as the nonindex crimes and crimes not included in the UCR program. The result is that the victimization statistics are somewhat limited in their representativeness and generalizability.

An important limitation of the design of the NCVS is a strength of the UCR—its almost complete coverage (98 percent) of the total United States population and the resultant ability to examine the geographic and ecological distribution of crime from the national level to the levels of regions, states, counties, Standard Metropolitan Statistical Areas, cities, and local communities. Historically, data on victimization have been collected from a sample of the population, which has varied around 100,000 respondents, distributed geographically throughout the United States. There are simply not enough data to generate meaningful and useful statistics for each of the geographic and ecological units represented in the UCR. This would require a comprehensive census of households, the cost of which would be prohibitive.

Another design problem is referred to as bounding, or the time frame used as the reference period in interviews, which is established at the first interview on a six-month cycle for "household location." This is done to fix the empirically determined optimum recall period of six months and to avoid double reporting of the same crime incident by respondents. The bounding of household locations rather than of the occupants of the household has also been a problem. If the occupants move, the new occupants are not bounded, and it has been estimated that about 10 to 15 percent of the sample consists of unbounded households. This factor, coupled with the mobility of the sample, creates a related problem: complete data records covering the three-year span of each panel are available for perhaps only 20 percent of the respondents. This restricts general data analysis possibilities, particularly the feasibility and utility of these data for longitudinal analyses of victimization experiences (Fienberg).

Finally, there are the inevitable counting problems: When there is more than one perpetrator involved in a crime, it is particularly difficult for respondents to report the number of victimizers with accuracy. The typical impersonality of a household burglary makes it impossible for a victim to know the number or characteristics of the burglars. Even as personal a crime as aggravated assault often presents the victim with problems in accurately recalling his perceptions when more than one person attempted or did physical injury to his body. The respondent's reports, then, may be less accurate when the perpetrator could be seen or when there was more than one observable perpetrator. If a respondent reports multiple victimizers in a crime incident, whether a property crime or violent crime, it counts as one victimization—the general counting rule is "one victim, one crime." By itself this is not necessarily problematic, but if one compares victimization rates and official crime rates for property offenses (for which the UCR counting rule is "one incident, one crime"), there may be sufficient noncomparability of units to jeopardize the validity of the comparison. For example, a three-victim larceny would yield three reports of victimization but only one crime known to the police. A three-victim assault would yield three of each and present fewer problems of comparability. The perspectives of the victim and the police are different, as are those of the NCVS and the UCR in counting and recording crime incidents with different statistical outcomes and interpretations.

A more serious counting problem involves series victimizations or rapid, repeated similar victimization of an individual. For a victim, it can be very difficult to separate one crime from another if they are very similar and happen within a compressed time period. The consequence is that validity suffers and there is a tendency to "blur" the incidents and to further underestimate the number of victimizations. The questionnaire separates single and series incidents, which are defined as three or more similar crimes that the respondent cannot differentiate in time or place of occurrence. Early publications of the NCVS excluded these series victimizations from the published victimization rates, raising the possibility that the rates are underestimations. Even more of the dark figure of hidden crime might be illuminated. If this and other problems with victimization surveys are resolved, the discrepancy between the amount of crime committed and the amount eventually reported to the police may become more substantial. There is little evidence that victims (except those of forcible rape) are changing their patterns of reporting crimes to the police, but there is mounting and more rigorous evidence that our ability to measure the amount and distribution of the dark figure of unreported crime is improving.

Self-report surveys. Surveys of self-reported criminal involvement are an important part of the improved capacity to illuminate the dark figure, in this case from the perspective of the criminal (or victimizer). The origin of self-report surveys predated victimization surveys by more than twenty years. Preliminary, groundbreaking research on self-reported hidden crime was conducted in the 1940s, but the method of simply asking someone about the nature and extent of his own criminal involvement did not become a recognized standard procedure until the late 1950s, with the work of James Short and Ivan Nye.

Austin Porterfield first used this variation of the survey research method of "self-disclosure" by a respondent in 1946, to compare the self-reports of college students regarding their delinquent activities while they were in high school with self-reports of delinquents processed through the juvenile court. Not only were more offenses admitted than detected, but also more significantly, it appeared that the college students had been involved in delinquency during their adolescence in ways similar to those of the officially defined delinquents. These findings suggested that the distinction between delinquent and nondelinquent was not dichotomous, but rather more continuous, and that crime was perhaps distributed more evenly in the American social structure than official statistics would suggest. Fred Murphy, Mary Shirley, and Helen Witmer reported in 1946 that the admissions of delinquent activities by boys who participated in a delinquency prevention experiment significantly surpassed the number of offenses that came to the attention of juvenile authorities. James Wallerstein and Clement Wyle conducted a study that remains unique in self-report research because it surveyed a sample of adults in 1947. They discovered that more than 90 percent of their sample of about fifteen hundred upper-income "law-abiding" adults admitted having committed at least one of forty-nine crimes included in the questionnaire.

These early self-report survey findings confirm empirically what criminal statisticians, law enforcement authorities, and even the public had known since the time of Quetelet—that a substantial volume of crime never comes to the attention of the criminal justice system. The hint that some of this invisible crime is committed by persons who are not usually considered candidates for official recognition as criminals was even more revelatory and intriguing, but remained dormant for a decade.

Heeding suggestions that criminology needed a "Kinsey Report" on juvenile delinquency, Short and Nye in 1957 developed an anonymous, self-administered questionnaire that contained a checklist of delinquent acts, which was administered to populations of students and incarcerated delinquents. Their research had a more profound and longer-lasting impact because it was tied to theory-testing and construction (Nye) and, more importantly, because it provocatively verified the hint only alluded to in the earlier self report-studies—that crime is not disproportionately a phenomenon of the poor, as suggested by official crime statistics. The self-report data were apparently discrepant with the official data because they showed that self-reported delinquency was more evenly distributed across the socioeconomic status scale than official delinquency. This one provocative finding called into question the correlates and theories of juvenile delinquency and crime because most were based on official crime statistics and that period's depiction of crime and delinquency as a phenomenon of the poor. The controversy set off by the work of Short and Nye still continues.

Literally hundreds of similar studies have been carried out since Short and Nye's pioneering work, most with similar results: there is an enormous amount of self-reported crime that never comes to the attention of the police; a minority of offenders commits a majority of the offenses, including the more serious crimes; the more frequently one commits crimes, the more likely is the commission of serious crimes; and those most frequently and seriously involved in crime are most likely to have official records. Self-report researchers have tended to assume that self-reports are valid and reliable—certainly more so than official measures. Ever since the mid-1960s, work critical of criminal justice agencies and of official crime statistics generated further support for these assumptions. A few theorists, such as Travis Hirschi, even constructed and tested delinquency theories based on self-report measures and their results.

It has been suggested, "confessional data are at least as weak as the official statistics they were supposed to improve upon" (Nettler, p. 107). This criticism is damning to the extent that the statistics produced by the self-report method and official statistics are valid and reliable measures of crime: if one rejects official statistics, then one should also question the adequacy of self-report statistics. Furthermore, as with official records and victimization surveys, there are a number of problems with the self-report method. Some of these are problems shared by victimization surveys and self-report surveys, and others are unique to the latter. The shared problems are the basic threats to the validity and reliability of responses to survey questions, including memory decay, telescoping, deceit, social-desirability response effects, and imprecise bounding of reference periods. The unique problems fall into four categories: inadequate or unrepresentative samples, unrepresentative domains of behavior measured, validity and reliability of the method, and methods effects.

Whereas the national victimization surveys cannot provide refined geographical and ecological data because of the dispersion of the probability samples across the United States, self-report surveys have other problems of representativeness and generalizability because they do not typically use national samples. Practically all self-report research is conducted with small samples of juveniles attending public schools in a community that, characteristically, is relatively small, often suburban or rural, and modally middle-class and white. This, of course, restricts the ability to generalize beyond these kinds of sample characteristics to adults, juveniles who are not in school, those who refuse to participate, urban inner-city juveniles, and poor and nonwhite youngsters. Such "convenience" samples also create analytic problems because data on those variables that are correlated with delinquency are simply unavailable or underrepresented in the sample. In short, most self-report research has somewhat limited generalizability because of typical sample characteristics. On the other hand, unlike the NCVS or UCR, self-report surveys were not intended originally to produce national or even generalizable estimates of the amount of juvenile delinquency crime in the United States.

Self-report surveys were intended, however, to produce data on a variety of delinquent behaviors. Compared to the restricted range of index crimes included in the NCVS, the domain of behavior measured in self-report surveys is expansive, with as many as fifty illegal acts in a questionnaire not being uncommon. Such expansiveness, however, creates other problems. Historically, the juvenile court has had jurisdiction over both crimes and offenses that are illegal only for juveniles, usually referred to as status offenses and including truancy, incorrigibility, curfew violation, smoking, and drinking. Self-report surveys have correctly covered crimes and status offenses alike in studying juvenile delinquency, but in some cases there has been an overemphasis on the less serious offenses. To the extent that there is an overrepresentation of less serious and perhaps trivial offenses, self-report measures are inadequate measures of the kind of serious juvenile crime that is likely to come to the attention of authorities. This is important in describing accurately the characteristics of juvenile offenders and their behavior, as well as in comparing self-report and official data. Such comparison is crucial to validation research, where one needs to compare the same categories of behavior, including both content and seriousness, in order to assess the reciprocal validity of self-report and official measures. In criminology as elsewhere, one should not compare apples with oranges!

Unfortunately, there has been a dearth of this kind of careful validation research, as well as of systematic research on reliability. The accuracy and consistency of self-report surveys have been assumed to be quite acceptable, or, if questions have been posed, they have typically come from validity and reliability research on general social-science survey methods. For example, it has been assumed that anonymous surveys are more valid than signed surveys and that interviews are preferred over self-administered questionnaires. Yet no study had directly compared the validity, and only one had compared the reliability, of two or more self-report methods within the same study until the work of Michael Hindelang, Travis Hirschi, and Joseph Weis in 1981. In those isolated studies where validity and reliability were addressed, external validation criteria such as official record data have been used too infrequently.

Of course, critics have remained skeptical about the accuracy of responses from liars, cheaters, and thieves, as well as from straight and honorable persons. The latter are not motivated by deception or guile, but they may respond incorrectly because a questionnaire item has poor face validity meaning that it does not make sufficiently clear what is being asked and that the respondent is consequently more free to interpret, construe, and attribute whatever is within his experience and imagination. For example, a common self-report item, "Have you ever taken anything from anyone under threat of force?" is intended to tap instances of robbery. However, respondents might answer affirmatively if they had ever appropriated a candy bar from their kid sister. This problem of item meaning and interpretation is chronic in survey research, but it only remains problematic if no validation research is undertaken to establish face validity. Unfortunately, this has been the case in the development of self-report instruments.

There has been a basic inattention to the psychometric properties of self-report surveys and attendant methods effects on measurement. From the psychometric research that went into the development of the NCVS, it is clearer that the bounding practices in self-report research have been inadequate: the reference periods are typically too long and variable from study to study. Most self-report surveys ask whether a respondent has "ever" committed a crime, a few use the past "three years," some use the past "year," but very few use the past "six months" (or less), which was established as the optimum recall period for the national victimization surveys. This poses threats to the accuracy of responses since it is established that the longer the reference period, the more problems with memory decay, telescoping, and misinterpretation of events.

A related problem arises when the self-report researcher wants to find out how often within a specified period a respondent has committed a crime. A favored means of measuring the frequency of involvement has been the "normative" response category. A respondent is asked, "How often in the past year have you hit a teacher?" and is given a set of response categories that includes "Very often," "Often," "Sometimes," "Rarely," and "Never." One respondent can check "Rarely" and mean five times, whereas another can check the same response and mean one time. They each respond according to personal norms, which are tied to their own behavior, as well as to that of their peers. This creates analytic problems because one cannot norm (that is, accurately compare) the answers of each respondent, obviating meaningful comparisons. A great deal of information is thus lost. Simply asking each respondent to record the actual frequency of commission for each offense can solve these problems.

Finally, unlike the NCVS and the UCR, there is very little about self-report surveys—whether their samples, instruments, or procedures—that is "standardized." This restricts the kinds of comparison across self-report studies that could lead to more improvements in the method and provide a more solid empirical foundation for theory construction and testing, as well as the possibility of nationwide self-report statistics comparable to those of the NCVS and the UCR.

This lack of standardization, inadequacies of samples, and the question of the differential validity and reliability of self-report and official measures of crime have led to two important developments in the research of crime statistics. The first is the initiation of surveys of national representative samples of juveniles for the purpose of estimating the extent and nature of delinquency and of substance abuse in the United States. The second is the conducting of more rigorous and comprehensive research on the differential validity and reliability of official, as compared to self-report, measures of crime and delinquency. In 1967, the National Institute of Mental Health initiated the first of an interrupted but relatively regular series of National Youth Surveys of a representative sample of teenage youths, who were interviewed about a variety of attitudes and behaviors, including delinquent behavior. This survey was repeated in 1972, and in 1976 the National Institute for Juvenile Justice and Delinquency Prevention became a cosponsor of what has become an annual self-report survey of the delinquent behavior of a national probability panel of youths aged from eleven to seventeen years. The two major goals are to measure the amount and distribution of self-reported delinquent behavior and official delinquency and to account for any observed changes in juvenile delinquency.

These periodic national self-report surveys allow more rigorous estimation of the nature and extent of delinquent behavior. It is ironic, however, that the validity, reliability, and viability of the self-report method as an alternative or adjunct to official measures was not assessed rigorously until Hindelang, Hirschi, and Weis began a study of measurement issues in delinquency research, focusing on the comparative utility of self-report and official data.

Within an experimental design, a comprehensive self-report instrument was administered to a random sample of sixteen hundred youths from fourteen to eighteen years of age, stratified by sex, race (white or black), socioeconomic status (high or low), and delinquency status (nondelinquent, police contact, or court record). Officially defined delinquents, boys, blacks, and lower-socioeconomic-status subjects were oversampled in order to facilitate data analysis within those groups that are often underrepresented in self-report studies. Subjects were randomly assigned to one of four test conditions that corresponded to four self-report methods of administration: anonymous questionnaire, signed questionnaire, face-to-face interview, and blind interview. A number of validation criteria were utilized, including the official records of those subjects identified in a reverse record check, a subset of questions administered by the randomized response method, a deep-probe interview for face validity testing a subset of delinquency items, and a follow-tip interview with a psychological-stress evaluator to determine the veracity of responses. The subjects were brought to a field office, where they answered the questions within the method condition to which they were randomly assigned. This experimental design, coupled with a variety of external validation criteria and reliability checks, ensures that the findings and conclusions can be drawn with some confidence—undoubtedly with more confidence than in any prior research on validity and reliability in the measurement of delinquency.

Hindelang, Hirschi, and Weis's study produced a variety of findings on the whole range of previously identified methodological problems and issues. Official crime statistics, it concluded, generate valid indications of the sociodemographic distribution of delinquency. Self-reports, indeed, measure a domain of delinquent behavior that does not overlap significantly with the domain covered by official data, particularly for the more serious crimes. However, self-reports can measure the same type and seriousness of delinquent behaviors as are represented in official records. Within the domain of delinquent behavior that they do measure, self-reports are very reliable, and basically valid. Self-report samples have been inadequate in that they do not include enough officially defined delinquents, nonwhites, and lower-class youths to enable confident conclusions to be drawn regarding the correlates of the more serious delinquent acts for which a juvenile is more likely to acquire an official record. Delinquency, whether measured by official or self-report data, is not equally distributed among all segments of society—there are real differences between those youngsters who engage in crime and those who do not. Methods of administration have no significant effects on the prevalence, incidence, validity, or reliability of self-reports. There is apparently less validity in the self-reports of those respondents with the highest rates of delinquency—male, black, officially defined delinquents. Perhaps the most significant finding of the research is related to this finding of differential validity for a small subpopulation of respondents. As originally proposed by Hindelang, Hirschi, and Weis in 1979, the empirical evidence shows that there is no discrepancy in the major correlates of self-reported or official delinquency, except for race, which may be attributable to the less valid responses of black subjects, particularly males with official records of delinquency.

The finding that self-reports and official measures do not produce discrepant results regarding the distribution and correlates of delinquency, but rather show convergence, is a critical piece of evidence in the controversy that has existed among criminal statisticians since the dark figure was identified at the beginning of the nineteenth century. Does the distribution of crime look the same when those crimes not known to the police are included in the overall distribution and with the distribution of crimes known to the police? Are the different sources of crime statistics producing discrepant or convergent perspectives of crime?