Charles R. Tittle
Control balance theory (CBT) was developed in the mid-1990s, primarily to illustrate a particular method for building integrated theory and to show how general theories are useful in addressing various issues in studies of crime and deviance. A major theme on which the theory has been built is the idea that deficient control, a well-established classic notion, and excessive control all can have deviogenic consequences. In addition, the theory rests on expectations that sufficient explanation will necessarily involve complex arguments. Thus, CBT not only attempts to explain the phenomena within its domain, but it also challenges simplistic theories, contentions that theoretical integration is both impossible and undesirable, and neglect of contingencies in theorizing.
State-corporate crime is defined as criminal acts that occur when one or more institutions of political governance pursue a goal in direct cooperation with one or more institutions of economic production and distribution. This concept has been advanced to examine how corporations and governments intersect to produce social harm. The complexity of state-corporate crime arises from the nature of the offenses; unlike traditional “street crime,” state-corporate crime is not characterized by the intent of a single actor to violate the law for personal pleasure or gain. Criminal actions by the state often lack an obvious victim, and diffusion of responsibility arising from corporate structure and involvement of multiple actors makes the task of attributing criminal responsibility difficult. Sufficient understanding of state-corporate crime cannot be gained through studying individual actors; one must also consider broader organizational and societal factors.
Further subclassification illuminates the different types of state-corporate crime: State-initiated corporate crime (such as the 1986 Space Shuttle Challenger explosion) occurs when corporations, employed by the government, engage in organizational deviance at the direction of, or with the tacit approval of, the government. State-facilitated state-corporate crime (such as the 1991 Imperial Food Products fire in Hamlet, North Carolina) occurs when government regulatory institutions fail to restrain deviant activities either because of direct collusion between business and government or because they adhere to shared goals whose attainment would be hampered by aggressive regulation.
David O. Friedrichs
Critical criminology has achieved a substantial presence within the field of criminology over the past several decades. Critical criminology has produced a framework for the understanding of crime and criminal justice that challenges core premises of mainstream criminology. Critical criminology emerged—principally from about 1980 on—in relation to radical (and “new”) criminology in the 1970s, and various influential societal developments and forces associated with the Sixties. The roots of critical criminology can be located in Marxist theory, in the work of Willem Bonger, and in that of other scholars who were not self-identified radicals—including Edwin H. Sutherland. Interactionist (labeling) theory and conflict theory provided an important point of departure for the development of radical—and subsequently critical—criminology. More specifically, the Berkeley School of Criminology in the United States and the National Deviancy Conferences in the United Kingdom were influential sources for the emergence of critical criminology. The core thesis of critical criminology can be most concisely summarized as a critique of domination, inequality, and injustice. Starting with the definition of “crime” itself, critical criminologists expose the biases and political agenda of mainstream criminology and advance an alternative approach to understanding crime and criminal justice. That said, some different choices are made by self-identified critical criminologists in terms of underlying assumptions, methodological preferences, and different forms of activist engagement. A call for news-making criminology, or a form of public criminology, is one theme for activism: direct political mobilization is another. The term “critical criminology” today is best understood as an umbrella term encompassing a wide range of different perspectives with quite different core concerns. Some of these strains were more dominant at an earlier time; some have emerged or become more prominent recently. The following are among the most enduring and consequential strains of critical criminology: neo-Marxist, critical race, left realist, feminist, crimes of the powerful, green, cultural, peacemaking, abolitionist, postmodern, postcolonial, border, and queer criminology. Some critical criminologists have called for replacing the core focus on crime with a focus on harm, broadly defined, and replacing criminology with zemiology, or the study of harm. Critical criminologists have concerned themselves with crimes of the powerful; gendered, sexualized harm and intimate partner violence; raced harm and racial oppression; hate crime; the war on drugs; the war on immigrants; police violence and the militarization of the police; mass incarceration and privatized criminal justice; carceral regimes; mass imprisonment; the death penalty, and alternative forms of justice including a form of restorative justice—among many other substantive concerns. The call for a Southern criminology that incorporates the outlook and concerns of the Global South is one significant development within critical criminology. Critical criminology has the potential to be of special relevance within the context of a historical period characterized by intense conflicts in relation to the political economy and civil society.
José A. Brandariz and Ignacio González-Sánchez
The influence of economic crises on crime and penality is one of the fundamental issues in economic analysis of the punitive field, and the topic has been explored from various perspectives in a wide range of criminology theories. From a criminal-motivation viewpoint, economic crises are seen to favor crime-rate growth because of their serious effects of increasing unemployment, increasing in poverty, and generating inequality. Similarly, diverse economic approaches to penality (though not all of them, for example, law- and economics-based theses) hold that economic crises usually produce a rise in punitiveness and a consequent rise in incarceration rates.
However, specialized academic literature has highlighted that the generally accepted view is far from accurate in all cases. Economic crises do not necessarily produce an increase in crime (at least not in all types of crime), nor do they always lead to an increase in punitiveness. Indeed, empirical studies about the effect of diverse economic crises (the Great Depression, the oil crisis of the 1970s, and the recent Great Recession) reveal an ambiguous panorama of the evolution in crime and penality.
The impact of economic turmoil on crime and punishment should be examined in all its complexity. Crime rates and incarceration rates are hardly correlated, and the latter are far more influenced by a variegated set of political, social, cultural, and economic forces than by changes in crime patterns themselves. To scrutinize the effect of economic determinants on the penal field, the analysis of economic crises and crime should therefore be separated from the analysis of economic crises and penality. Unfortunately, there is a shortage of academic literature and empirical data on the implications of pre-21st-century financial crises for crime and punishment. The recent Great Recession thus has great utility for delving into the consequences of periods of economic chaos on crime and punitiveness.
When Guenther Jakobs introduced the concept of “enemy criminal law” (Feindstrafrecht), or enemy penology, into the legal debate, this was due to a concern with the increasingly anticipatory nature of criminalization in German legislation in the last decades of the 20th century. Against the backdrop of a series of terror attacks in the West and the ensuing debates on how to deal with the dangers and threats of the new millennium, Jakobs’s theory gained new momentum in Germany’s public discourse and beyond. As it seems, the author himself turned the concept into a device for political intervention, declaring the notion of the enemy as indispensable for dealing with certain extreme crimes and notorious offenders, not only to prevent future crime and avert harm from society but also, and most notably, to preserve the established “citizen criminal law” (Bürgerstrafrecht): the enemy is the one to be isolated and excluded from the system. Enemy criminal law may be a peculiar legal concept. The logic of enemy penology, however, leads us to some more fundamental insights into the conundrums of liberal political thinking and attendant legal conceptions. It requires us to think about the enemy as a liminal figure that points to the preconditions and the paradoxes of our legal system. The history of criminology attests to the discipline’s struggle with penal law’s inherent limitations. And if we live today in times where exception and rule, internal security and external security, and military and police concerns increasingly overlap and intermingle in the face of ever new threats, the notion of enemy penology helps us to critically reflect on the mechanisms that drive these transformations.
Extortion as a crime has long attracted the interest of scholars, and much effort has been put into coining a precise definition that would allow distinguishing it from other similar predatory practices such as blackmail, bribery, coercion, and robbery. Academic literature classifies extortive practices according to their degree of complexity and involvement of organized crime. In this sense, the simplest form of extortion displays one offender who receives a one-time benefit from one victim, while the most sophisticated form is illustrated by racketeering, whereby an organized crime group systematically extorts money from multiple victims. Extortion as an organized crime activity can involve both episodic extortion practices and well-rooted systemic practices over a certain territory, where the latter is usually regarded as perpetrated by Mafia-type criminal organizations. Some scholars argue that extortion racketeering as a Mafia crime should be defined as sale and provision of extralegal protection services—protection of property rights, dispute resolution, and enforcement of contracts. However, others contend that extortion by Mafia-type organizations should not be counted as an economic activity but rather be considered as an illegal form of taxation imposed by quasi-political groups. In economic terms, it is a transfer of value and creates no economic output.
In contrast with the traditional understanding of extortion racketeering as “defining activity of organized crime,” some scholars have also focused on “extortion under the color of office,” or, in other words, extortion perpetrated by public servants or politicians in their official capacity. Extortion has often been compared with bribery, since both crimes can be defined as an unlawful conversion of properties and goods belonging to someone else for one’s own personal use and benefit. The debate on the differences between bribery and extortion, however, is a contested one, and has followed two lines of argument: respectively, the degree of coercion involved in the crime and the role (or modus operandi) of public officials in the bribery and extortive scheme. The common element for both crimes is the fact that representatives of the state abuse their power and official position for their own benefit.
James A. Densley
This article examines the who, what, where, when, why, and how of gang joining. The question of what youth join when they join gangs speaks to the contested nature of gang definitions and types and the consequences of gang membership, specifically heightened levels of offending and victimization. The type of gang and the obligations of membership influence the joining process. Where youth join gangs, namely, the neighborhood and social context, also impacts individual opportunities and preferences for joining. When youth join gangs is considered in a developmental sense, to include both adolescent and adult onset, in order to account for continuity and change in individual levels of immersion or “embeddedness” in gangs across the life course. Who joins gangs provides a profile of gang membership grounded in the well-documented risk factors for gang membership, but limited by problems of prediction. Why youth join gangs speaks to the push and pull factors for membership, the appeal of gangs, and the selective incentives they offer. Still, motivations for gang membership cannot fully explain selection into gangs, nor can general theories of crime that do not necessarily fit with general knowledge of gangs. How youth join gangs, for example, is more complicated than initiation rites. The mechanisms underlying the selection process can be understood through the lens of signaling theory, with implications for practice.
Christian L. Bolden
Gang organization has been an aspect of research that is often explored and debated. The concept of organization is intertwined with questions of whether gangs have leaders, whether gangs can be considered organized crime, which groups are actually street gangs, and other related questions. Though there are some crossover categories, street gangs are viewed as distinctly different than organized crime groups, prison gangs, outlaw motorcycle clubs, skinheads, stoners, and taggers.
Gang structures are widely varied, with a few being highly organized and most being loose networks of associates. The organization of a gang may change over time. There is an array of membership types that range from core members who might maintain affiliation well into adulthood to temporary members who only spend a short time in the gang. Gangs may have sub-group clique structures based on age-graded cohorts, neighborhoods, or criminal activity. Leadership roles in gangs rarely take the form of a recognizable figurehead.
These variations have led to a plethora of gang categories that include evolutionary typologies that place gangs by their stage in criminal sophistication, behavioral typologies that identify gangs by the type of criminal behavior the members engage in, and structural typologies that differentiate gangs by the characteristics of their composition. It is important to note that most of the following gang typologies are focused on gangs in the United States and may not be as relevant in other countries.
Major gang affiliations are also explored. Like other aspects of organizations, affiliations are not stable, as gang alliances are volatile. Despite the ability of affiliations to fluctuate, this categorization strategy is commonly used outside of academic research.
General strain theory (GST) provides a unique explanation of crime and delinquency. In contrast to control and learning theories, GST focuses explicitly on negative treatment by others and is the only major theory of crime and delinquency to highlight the role of negative emotions in the etiology of offending. According to GST, the experience of strain or stress tends to generate negative emotions such as anger, frustration, depression, and despair. These negative emotions, in turn, are said to create pressures for corrective action, with crime or delinquency being one possible response.
GST was designed, in part, to address criticisms leveled against previous versions of strain theory. Earlier versions of strain theory have been criticized for focusing on a narrow range of possible strains, for their inability to explain why only some strained individuals resort to crime or delinquency, and for limited empirical support. GST has been partly successful in overcoming these limitations. Since its inception, the theory has received a considerable amount of attention from researchers, has enjoyed a fair amount of empirical support, and has been credited with helping to revitalize the strain theory tradition. The full potential of GST has yet to be realized, however, as the theory continues to evolve and further testing is required.
Michael Leitner, Philip Glasner, and Ourania Kounadi
The most prominent law in geography is Tobler’s first law (TFL) of geography, which states that “everything is related to everything else, but near things are more related than distant things.” No other law in geography has received more attention than TFL. It is important because many spatial statistical methods have been developed since its publication and, especially since the advent of geographic information system (GIS) and geospatial technology, have been conceptually based on it. These methods include global and local indicators of spatial autocorrelation (SA), spatial and spatial-temporal hotspots and cold spots, and spatial interpolation. All of these are highly relevant to spatial crime analysis, modeling, and mapping and will be discussed in the main part of this text.
Jason Gravel and George E. Tita
Though often not mentioned by name, the importance of social networks in explaining criminal behavior, delinquency, and patterns has long been recognized in the study of crime. Theories that explain criminal behavior at the individual level being learned through the impacts of peer influences presume that the transmission of ideas and influences flow among social ties (networks) that link individuals. Cultural theories of crime work in the same way. At the community level, delinquency and criminal behavior are born among members of a community or group that adhere to a particular cultural set of norms or beliefs. The concentration of crime in particular geographic areas results when there are insufficient ties among local residents to affect informal social control in the area. Impacted neighborhoods are often described as socially isolated, lacking social ties to institutions of power that provide the investment and services needed in a healthy community. The history of the formation and activities of street gangs is a clear example of how understanding the ties among individuals, and between groups of these individuals, matter in our understanding these phenomena. Comprehending social ties among gangs and gang members and employment of social network analysis (SNA) have become mainstays of local law enforcement efforts to address the issue of gang violence.
Much of the early criminological work that implicated social networks but did not explicitly acknowledge a network by name, or did not employ SNA on formal network data, did so because collecting such data is difficult at best and sometimes impossible. Though criminology has been a “late adopter” of SNA, the field is making great strides in this area. The National Longitudinal Study of Adolescent to Adult Health (Add Health) research program has provided a rich set of network data to explore issues of peer influence. Researchers are using carefully collected social network data at the individual and organizational level to better understand the ability of communities to self-regulate delinquency and crime in an area. Arrest data and field identification stops are being used to generate large networks in an effort to understand how one’s position in a larger social structure might be related to an actor’s involvement in future offending or victimization.
As the field of criminology continues to adopt a network perspective in the study of crime, it is important to understand the development of social networks within the field. Critically examining the strengths and weaknesses of network data, especially in terms of the process by which data are generated, can lead to better applications of network analysis in the future.
Breanna Boppre, Emily J. Salisbury, and Jaclyn Parker
Scholarship in criminology has focused on individuals’ pathways to crime—how life experiences, often beginning during childhood, lead to criminality in adolescence or adulthood. General frameworks for this research include life-course, developmental, and biosocial criminology. However, because the vast majority of the general pathways research literature was developed using samples of boys and men, scholars with a feminist theoretical background argue that such research is not truly representative of girls and women’s pathways to crime. While general theories of crime have been applied broadly, gender-specific pathways to crime account for important distinctions between male and female experiences.
Thus, gender (and sex), through biological differences, social norms, and expectations, shapes individual life experiences that result in distinct pathways to crime for men and women. Consequently, understanding criminality requires a full consideration of gendered experiences. Even though similar life events may occur with both men and women, individual responses and effects can vary greatly and lead to different pathways to criminal behavior. Accordingly, this article discusses pathways to crime though a gendered lens. First, men’s pathways to crime are presented, which have been traditionally represented through general criminological research. Next, women’s specific pathways to crime are discussed, developed primarily through the gendered pathways literature. Finally, future directions in pathways research are outlined.
Zelia A. Gallo
The literature on contemporary Western punishment presents us with a number of possible approaches to political ideologies and penality. The first approach requires us to ask what different political ideologies have to say about crime and punishment. This entails a close analysis of the ideologies’ main claims on matters of power, authority, and collective co-existence, to see if and how such claims have played out in the penal sphere. Analyses of social democratic penality serve here as useful case studies for such an approach. Such analyses also illustrate the second approach to questions of political ideology and penality. This approach requires us to ask what impact crime has had upon the fate of different ideologies. Have the changing incidence and changing perceptions of crime come to threaten the legitimacy of dominant ideologies? The third approach is that of critique of ideology: penality is studied as ideology, to discern what it conceals about reality and existing power relations. Here the analysis of contemporary UK offences of dangerousness acts as a case study for such an approach. To the extent that offences of dangerousness are rooted in neoliberalism, the discussion also introduces us to debates concerning neoliberalism and penality, in particular the idea that contemporary punishment expresses both the ascendancy of neoliberal doxa, and the decline of existing macro-ideologies such as social democracy. This decline can be seen as a move toward a post-ideological era, in which crime and punishment have come to replace political visions and utopias. However, recent scholarship on political ideologies argues that the latter are ubiquitous and permanent features of political thinking. This implies that the contemporary era cannot be described as post-ideological. Rather, it is an era in which macro-ideologies such as social democracy—which provided a holistic view of social order and comprehensive ideational resources to construct it—have been replaced by thin ideologies—which offer us narrower visions and ambitions. Examples of such thin ideologies include populism and technocracy. It is then possible to study the link between thin-ideologies and penality, a study that is here exemplified by the analysis of populism and penal populism, and technocracy and epistemic crime control. An analysis of thin ideologies and penality can also be undertaken with a normative project in mind, namely that of identifying within these thin ideologies, possible ideational resources that might be used to imagine a better penal future: one that is more moderate, more democratic, and less punitive.
Alessandro De Giorgi
The political economy of punishment is a critical approach within the sociology of punishment that hypothesizes the existence of a structural relationship between transformations of the economy and changes in the penal field. Inspired by a neo-Marxist framework, this materialist critique of punishment explores—from both a historical and a contemporary perspective—the connections between the reorganization of a society’s system of production and the emergence, persistence, or decline of specific penal practices. Thus, materialist criminologists have investigated the parallel historical emergence of factories as the main sites of capitalist production and of prisons as the main institutions of punishment in modern societies. Scholars in the field have also explored the correlations between incarceration rates and socioeconomic indicators, such as unemployment rates, poverty levels, welfare regimes, and labor markets. This materialist framework has been criticized in mainstream criminological literature for its alleged economic determinism. In particular, critiques have focused on the theory’s tendency to overlook the cultural significance of punishment and the politico-institutional dimensions of penality, as well as on its exclusive emphasis on the instrumental side of penal practices as opposed to their symbolic dimensions. In response to these critiques, some recent works have tried to integrate the old political economy of punishment with epistemological tools from different disciplinary fields in order to overcome some of the limitations of the materialist approach. This broadening of the structural paradigm in criminology could point toward the envisioning of a “cultural political economy of punishment.” Particularly in its more recent iterations, the materialist critique of punishment provides a powerful lens for investigating current transformations in the penal field, such as the advent of mass incarceration and the ongoing prison crisis in the United States.
Gottfredson and Hirschi advanced self-control theory in 1990 as part of their general theory of crime. Self-control is defined as the ability to forego acts that provide immediate or near-term pleasures, but that also have negative consequences for the actor, and as the ability to act in favor of longer-term interests. An individual’s level of self-control is influenced by family or other caregiver behavior early in life. Once established, differences in self-control affect the likelihood of delinquency in childhood and adolescence and crime in later life. Persons with relatively high levels of self-control do better in school, have stronger job prospects, establish more stable interpersonal relationships, and attain higher income and better health outcomes. Self-control theory was initially constructed to reconcile the age, generality, and stability findings of criminological research with the standard assumptions of control theory. As such, it acknowledges the general decline in crime with age, versatility in types of problem behaviors engaged in by delinquents and offenders, and the generally stable individual differences in the tendency to engage in delinquency and crime over one’s life-course. Self-control theory applies to a wide variety of illegal behaviors (most crimes) and to many noncrime problem behaviors, including school problems, accidents, and substance abuse.
A considerable amount of research has been undertaken on self-control theory and on Gottfredson and Hirschi’s general theory of crime. As a result, self-control theory is likely the most heavily researched perspective in criminology during the past 30 years. Most reviews find substantial empirical support for the principal positions of the theory, including the relationship between levels of self-control and delinquency, crime, and other problem behaviors. These relationships appear to be strong throughout life, among most groups of people, types of crime, in the United States and other countries, and over time. The posited important role of the family in the genesis of self-control is consistent with substantial bodies of research, although some researchers argue in favor of important genetic components for self-control. The theory’s expectations about the age distribution of crime, versatility of offending, and stability of individual differences over long periods of time also receive substantial support. Researchers have long studied variations in age effects, particularly seeking continuously high levels of offending for the most serious offenders, but reviewers have found that the evidence for meaningful variability is not convincing.
For public policy, self-control theory argues that the most promising approach for crime reduction focuses primarily on prevention, especially in early childhood, and secondarily on situational prevention for specific types of crimes. Gottfredson and Hirschi argue that self-control theory is inconsistent with reliance on the criminal justice system to affect crime levels. On the one hand, general reviews of the empirical literature on deterrence and incapacitation support the expectations of self-control theory by finding little support for severity of sanctions, sanctions long removed from the act, and selective incapacitation for “serious offenders.” On the other hand, experimental studies from education, psychology, and criminology generally support the idea that early-childhood family and educational environments can be altered to enhance self-control and lower expected delinquency, crime, and other problem behaviors later in life.
Contemporary sociologists typically trace social disorganization models to Emile Durkheim’s classic work. There is continuity between Durkheim’s concern for organic solidarity in societies that are changing rapidly and the social disorganization approach of Shaw and McKay (1969). However, Shaw and McKay view social disorganization as a situationally rooted variable and not as an inevitable property of all urban neighborhoods. They argued that socioeconomic status (SES), racial and ethnic heterogeneity, and residential stability account for variations in social disorganization and hence informal social control, which in turn account for the distribution of community crime. Empirical testing of Shaw and McKay’s research in other cities during the mid-20th century, with few exceptions, focused on the relationship between SES and delinquency or crime as a crucial test of the theory. As a whole, that research supports social disorganization theory. A handful of studies in the 1940s through early 1960s documented a relationship between social disorganization and crime. After a period of stagnation, social disorganization increased through the 1980s and since then has accelerated rapidly. Much of that research includes direct measurement of social disorganization, informal control, and collective efficacy. Clearly, many scholars perceive that social disorganization plays a central role in the distribution of neighborhood crime.
Richard B. Felson
Since criminal violence involves doing harm to someone (as well as rule breaking) a theory of aggression is needed to help explain it. A social interactionist (SI) theory of aggression fits the bill. According to this perspective there are strong incentives for aggression. Sometimes individuals harm or threaten to harm others in order to force compliance. They compel the target to do something for them or deter them from doing something that offends them. Sometimes they punish someone who offends them in order to achieve justice or retribution. They feel morally justified and self-righteous about their behavior. Sometimes they are attempting to assert or protect their self- or social image. Finally, some violence involves thrill seeking. These are basic motives of human behavior, and they can readily explain the incentives for both verbal and physical aggression.
An SI perspective is a challenge to frustration-aggression approaches (including general strain theory) that claim that aversive stimuli and negative affect instigate aggression. Negative affect plays a much more limited causal role in producing violence from an SI perspective. A bad mood after an aversive experience may facilitate an aggressive response if people fail to consider costs and moral inhibitions when they are in a bad mood. The aversive experience does not instigate aggression unless the person responsible is assigned blame. Blame is critical because it leads to a grievance and a desire for retribution.
Some acts of criminal violence are predatory, and some stem from verbal disputes. The violence of the robber, the rapist, and the bully are usually predatory. Most homicides and assaults stem from disputes. It is therefore important to study the social interaction during disputes in order to understand why they sometimes escalate to violence. A social interactionist approach suggests it is important to study interpersonal conflict that underlies dispute-related violence, since conflict often leads to grievances. Cooperative face-work (i.e., politeness) prevents violence because it avoids attacks on selves. When such attacks occur, they tend to lead to retaliation and the possibility of escalation. Third parties can influence the outcome if they instigate or mediate the dispute, or just serve as a passive audience. Mediators can allow both sides to back down without losing face, but they can also encourage weaker parties to fight. Finally, violence can be considered a form of informal social control when social control by third parties is ineffective.
An SI approach emphasizes the importance of adversary effects (i.e., the physical threat posed by adversaries). People take into account the relative coercive power of their opponent when they decide whether to engage in violence and what tactics to use. If they attack adversaries who are physically stronger, they may rely on weapons or allies. Adversary effects explain why armed violence spreads across a community and why it lowers rates of unarmed violence. They help to explain variation in violent crime across nations, regions, and racial/ethnic groups.
Anthony Petrosino, Claire Morgan, and Trevor Fronius
Systematic reviews and meta-analyses have become a focal point of evidence-based policy in criminology. Systematic reviews use explicit and transparent processes to identify, retrieve, code, analyze, and report on existing research studies bearing on a question of policy or practice. Meta-analysis can combine the results from the most rigorous evaluations identified in a systematic review to provide policymakers with the best evidence on what works for a variety of interventions relevant to reducing crime and making the justice system fairer and more effective. The steps of a systematic review using meta-analysis include specifying the topic area, developing management procedures, specifying the search strategy, developing eligibility criteria, extracting data from the studies, computing effect sizes, developing an analysis strategy, and interpreting and reporting the results.
In a systematic review using meta-analysis, after identifying and coding eligible studies, the researchers create a measure of effect size for each experimental versus control contrast of interest in the study. Most commonly, reviewers do this by standardizing the difference between scores of the experimental and control groups, placing outcomes that are conceptually similar but measured differently (e.g., such as re-arrest or reconviction) on the same common scale or metric. Though these are different indices, they do measure a program’s effect on some construct (e.g., criminality). These effect sizes are usually averaged across all similar studies to provide a summary of program impact. The effect sizes also represent the dependent variable in the meta-analysis, and more advanced syntheses explore the role of potential moderating variables, such as sample size or other characteristics related to effect size.
When done well and with full integrity, a systematic review using meta-analysis can provide the most comprehensive assessment of the available evaluative literature addressing the research question, as well as the most reliable statement about what works. Drawing from a larger body of research increases statistical power by reducing standard error; individual studies often use small sample sizes, which can result in large margins of error. In addition, conducting meta-analysis can be faster and less resource-intensive than replicating experimental studies. Using meta-analysis instead of relying on an individual program evaluation can help ensure that policy is guided by the totality of evidence, drawing upon a solid basis for generalizing outcomes.