The meta‐analysis of partial effect sizes

This paper discusses the synthesis of partial effect sizes derived from multivariate settings. The general statistical properties of the d‐effect size are derived, extending Hedges's statement of zero‐order properties. These general properties have direct relevance in the synthesis of a set of independent effect sizes arising from empirical studies predicated on a common theoretical model. We discuss possible solutions to the problem of comparing effect sizes arising from models employing differing sets of covariates. We apply the general statistical properties in the synthesis of gender performance differences in first‐level economics courses at three New Zealand universities. The model of academic performance is based on Spearman's conception of general academic ability and specific ability in economics.     

The relative impact of workplace bullying as a social stressor at work

Hauge, L. J., Skogstad, A. & Einarsen, S. (2010). The relative impact of workplace bullying as a social stressor at work. Scandinavian Journal of Psychology, 51, 426–433. Exposure to workplace bullying has been argued to be a severe social stressor and a more crippling and devastating problem for affected individuals than the effects of all other work‐related stressors put together. However, few studies have explicitly investigated this assumption. In a representative sample of the Norwegian working population, the present study investigated the relative contribution of workplace bullying as a predictor of individual and organizational related outcomes after controlling for the well‐documented job stressors of job demands, decision authority, role ambiguity and role conflict. Bullying was found to be a significant predictor of all the outcomes included, showing a substantial relative contribution in relation to anxiety and depression, while for job satisfaction, turnover intention and absenteeism, more modest relative contributions were identified. Workplace bullying is indeed a potent social stressor with consequences similar to, or even more severe than, the effects of other stressors frequently encountered within organizations. Thus, the finding that bullying has a considerable effect on exposed individuals also when controlling for the effects of other job stressors demonstrates bullying as a serious problem at workplaces that needs to be actively prevented and managed in its own right.     

The predictive validity of cognitive ability tests: A UK meta‐analysis

A meta‐analysis on the validity of tests of general mental ability (GMA) and specific cognitive abilities for predicting job performance and training success in the UK was conducted. An extensive literature search resulted in a database of 283 independent samples with job performance as the criterion (N=13,262), and 223 with training success as the criterion (N=75,311). Primary studies were also coded by occupational group, resulting in seven main groups (clerical, engineer, professional, driver, operator, manager, and sales), and by type of specific ability test (verbal, numerical, perceptual, and spatial). Results indicate that GMA and specific ability tests are valid predictors of both job performance and training success, with operational validities in the magnitude of .5–.6. Minor differences between these UK findings and previous US meta‐analyses are reported. As expected, operational validities were moderated by occupational group, with occupational families possessing greater job complexity demonstrating higher operational validities between cognitive tests and job performance and training success. Implications for the practical use of tests of GMA and specific cognitive abilities in the context of UK selection practices are discussed in conclusion.     

A meta‐analysis of the predictors and consequences of organization‐based self‐esteem

Organization‐based self‐esteem (OBSE), which represents employees' beliefs about their own value and competence as organizational members, has attracted much recent research attention. In the current paper, we identified several theoretically based predictors and consequences of OBSE. We then conducted a meta‐analysis examining the relationships between OBSE and these variables. Results indicated that several hypothesized predictors, including the work environment and employee dispositions, were related to OBSE. Furthermore, OBSE was related to several hypothesized outcome variables including job satisfaction, organizational commitment, employee health, job performance, and organizational citizenship behaviour. As expected, OBSE generally yielded stronger relationships with work‐related variables than did general self‐esteem and we found evidence that OBSE mediated the relationships between general self‐esteem and work‐related criteria.     

How to do a meta‐analysis

Meta‐analysis is a statistical tool for estimating the mean and variance of underlying population effects from a collection of empirical studies addressing ostensibly the same research question. Meta‐analysis has become an increasing popular and valuable tool in psychological research, and major review articles typically employ these methods. This article describes the process of conducting meta‐analysis: selecting articles, developing inclusion criteria, calculating effect sizes, conducting the actual analysis (including information on how to do the analysis on popular computer packages such as IBM SPSS and R) and estimating the effects of publication bias. Guidance is also given on how to write up a meta‐analysis.     

A meta‐analysis of serotonin metabolite 5‐HIAA and antisocial behavior

During the past 25 years, researchers have examined the relationship between neurochemical variables and antisocial behavior in human adults, but none has been studied more intensely than the serotonin metabolite 5‐hydroxyindoleacetic acid (5‐HIAA). The goal of the current study was to employ meta‐analytic procedures to quantitatively evaluate selected evidence on the relationship between 5‐HIAA and antisocial behavior. It was expected that antisocial groups would show reduced cerebrospinal fluid 5‐HIAA compared with non–antisocial groups. This study also aimed to assess moderators that could influence the relationship between 5‐HIAA and antisociality. An electronic search and strict inclusion criteria identified 20 reports used in this meta‐analysis. Results showed a significant overall mean effect size (ES = –.45, P < .05) in the direction of lowered 5‐HIAA in antisocial vs. non–antisocial groups. A significant moderating effect for age indicated that groups comprised of antisocial individuals younger than 30 years exhibited larger negative effect sizes (ES = –1.37, P < .05) than groups with older subjects (ES = –.31, P < .05). There were no moderating effects for gender, target of violence, history of suicide, and alcoholism. Age effects may help explain age‐related declines in crime. The fact that effects did not differ based on other moderating variables supports models of reduced serotonin in antisocial individuals, regardless of type of crime or psychiatric problems. Aggr. Behav. 28:299–316, 2002. © 2002 Wiley‐Liss, Inc.     

20 Years of workplace bullying research: A review of the antecedents and consequences of bullying in the workplace

Research on workplace bullying, which has just recently passed the 20 year mark, has grown significantly over this duration of time. We provide an extensive review of the extant literature, with a focus on the antecedents and consequences of workplace bullying. We organize our review of the extant literature by level of analysis, which allows us to understand workplace bullying from each major level of analysis, while simultaneously identifying those levels at which research has been sparse. We then develop a conceptual model based on our review that similarly depicts theoretical and/or empirical findings from the extant literature, but in a succinct manner. Based on our review and conceptual model, we identify and highlight a number of key avenues for future research that will help extend the current workplace bullying literature.     

Hypothesis tests for population heterogeneity in meta‐analysis

Choice of the appropriate model in meta‐analysis is often treated as an empirical question which is answered by examining the amount of variability in the effect sizes. When all of the observed variability in the effect sizes can be accounted for based on sampling error alone, a set of effect sizes is said to be homogeneous and a fixed‐effects model is typically adopted. Whether a set of effect sizes is homogeneous or not is usually tested with the so‐called Q test. In this paper, a variety of alternative homogeneity tests – the likelihood ratio, Wald and score tests – are compared with the Q test in terms of their Type I error rate and power for four different effect size measures. Monte Carlo simulations show that the Q test kept the tightest control of the Type I error rate, although the results emphasize the importance of large sample sizes within the set of studies. The results also suggest under what conditions the power of the tests can be considered adequate.     

A meta‐analysis of the differential relations of traditional and cyber‐victimization with internalizing problems

This meta‐analysis examined the associations between cyber‐victimization and internalizing problems controlling for the occurrence of traditional victimization. Twenty independent samples with a total of 90,877 participants were included. Results confirmed the significant intercorrelation between traditional and cyber‐victimization (r = .43). They both have medium‐to‐large bivariate correlations with internalizing problems. Traditional victimization (sr = .22) and cyber‐victimization (sr = .12) were also uniquely related to internalizing problems. The difference in the relations between each type of victimization and internalizing problems was small (differential d = .06) and not statistically significant (p = .053). Moderation of these effect sizes by sample characteristics (e.g., age and proportion of girls) and study features (e.g., whether a definition of bullying was provided to participants and the time frame used as reference) was investigated. Results are discussed within the extant literature on cyber‐aggression and cyber‐victimization and future directions are proposed.

     

Accounts of workplace bullying: The role of the organization

In over a decade of research into bullying at work, the focus has been on defining, measuring, and explaining the essential nature of the bullying phenomenon. This focus has positioned the individual as the main unit of analysis, with the organization acting as a facilitating backdrop. By assuming a critical research position as opposed to the dominant positivist tradition from which most of the bullying research emanates, attention can be drawn to additional and marginalized accounts. Our research does not offer a definition of bullying—rather, we examine the implications of the different ways in which the term bullying is used. This paper uses data from a case study in a large telecommunications company's call centres. We demonstrate that while employees use the pathologized individual and the facilitating environment to account for bullying, in addition they use the notion of the pathologized organization. This additional narrative brings issues of power and politics in organizations to the fore. Taking a critical management approach, we focus on employee accounts of the oppressive impact of power structures. We argue that marginalizing certain accounts functions to maintain the organizational power balance. By using the term bullying to describe their work experience, employees in this study sought to employ an emotive and highly charged term to highlight their discontent at increasingly difficult work situations.     

Job attitudes of part‐time vs. full‐time workers: A meta‐analytic review

A meta‐analysis was conducted (k =38, N =51,231) to examine the size of the difference between full‐ and part‐time employees on job attitudes. Results indicated that there was little difference between full‐time (FT) and part‐time (PT) employees on job satisfaction, organizational commitment, intentions to leave and facets of job satisfaction. Full‐time employees were found to be more involved with their jobs than PT employees (d_c=0.39). Moderating variables were examined (type of job, sex of the sample and sampling strategy used), but these variables explained little of the variability in effect sizes across the studies. An additional analysis of voluntary vs. involuntary employment status was conducted on job satisfaction, but only small differences were found. The theoretical implications are discussed.     

Improved Fisher z estimators for univariate random‐effects meta‐analysis of correlations

Several authors have studied or used the following estimation strategy for meta‐analysing correlations: obtain a point estimate or confidence interval for the mean Fisher z correlation, and transform this estimate to the Pearson r metric. Using the relationship between Fisher z and Pearson r random variables, I demonstrate the potential discrepancy induced by directly z‐to‐r transforming a mean correlation parameter. Point and interval estimators based on an alternative integral z‐to‐r transformation are proposed. Analytic expressions for the expectation and variance of certain meta‐analytic point estimators are also provided, as are selected moments of correlation parameters; numerical examples are included. In an application of these analytic results, the proposed point estimator outperformed its usual direct z‐to‐r counterpart and compared favourably with an estimator based on Pearson r correlations. Practical implications, extensions of the proposed estimators, and uses for the analytic results are discussed.     

Work‐place bullying: A group processes framework

Work‐place bullying is primarily conceptualized in the literature from an individual or interpersonal perspective with a focus on the victim. The impact of the broader organizational context on bullying has also been considered to a lesser extent. Only a small amount of research exists, however, regarding the group‐level processes that impact on the incidence and maintenance of bullying behaviour. We adopt a group level perspective to theoretically discuss and explain the processes involved in the occurrence and maintenance of work‐place bullying behaviours. Using Social Identity Theory ( Tajfel & Turner, 1986 ) and Social Rules Theory ( Argyle, Henderson, & Furnham, 1985 ), two conceptual frameworks are presented that consider work‐place bullying at the intra‐group and inter‐group levels. Several propositions are put forward regarding the likelihood of bullying in work groups. Suggested directions for empirical research are addressed and practical implications are also discussed.     

Employee proactivity in organizations: A comparative meta‐analysis of emergent proactive constructs

This meta‐analysis of 103 independent samples provides a comparative evaluation of the relationships associated with four emergent proactive constructs including proactive personality, personal initiative, voice, and taking charge. This study investigates comparative relationships among these focal proactive constructs and key organizational variables (i.e., job performance), personality traits (i.e., the Big Five), and individual variables (i.e., work experience). Results reveal significant correlations between proactivity and performance, satisfaction, affective organizational commitment, and social networking. Results also provide evidence that differentiates focal proactive constructs from the Big Five as well as individual differences in work experience, age, and general mental ability. Current progress towards a more integrative understanding of proactivity research is discussed.     

Children's meta‐perceptions and meta‐accuracy of acceptance and rejection by same‐sex and other‐sex peers

The goals of this study were to examine children's meta‐perceptions and meta‐accuracy of acceptance and rejection in the peer group, the degree to which these perceptions vary by perceiver sex and sex of the reference group, and the association between these perceptions and children's actual functioning in the peer group. Participants were 644 fourth‐grade children. Meta‐perceptions and meta‐accuracy were derived from sociometric nominations of actual and perceived acceptance and rejection. Children more accurately perceived how they were seen by same‐sex peers than how they were seen by other‐sex peers. They also perceived more rejection than acceptance from other‐sex peers. Meta‐accuracy for rejection was low regardless of the sex of the reference group. Sex of the reference group significantly moderated the association between meta‐perceptions and meta‐accuracy of acceptance and rejection and children's actual peer relationships. These findings indicate the importance of examining these relatively understudied social cognitions in research with children and the importance of taking the sex of the reference group into account in future peer relations studies using peer nomination methods.     

The impact of a peer counselling scheme to address bullying in an all‐girl London secondary school: A short‐term longitudinal study

Background A variety of peer support schemes are now widely used in schools, notably to reduce bullying. However, there has been little systematic investigation of the impact and effectiveness of these approaches. Aims To assess the impact of a peer counselling scheme on peer counsellors and the school community. Sample The research was conducted in a North London all‐girls state secondary school. Data were collected from all lower school classes (years 7, 8, and 9) and some staff members, in addition to year 10 peer counsellors and an age equivalent comparison group. Method A detailed 1‐year longitudinal study combined qualitative and quantitative methods of assessment. Results Peer counsellors benefited from their involvement through an acquisition of transferable communication and interpersonal skills, and, compared to age‐matched control pupils, had increased social self‐esteem. There were no reductions in self‐reported bullying and victimization, but in general pupils believed that there was less bullying in school and that the school was doing more about bullying, with year 7 students showing the most positive changes. Conclusions Peer‐counselling schemes can improve self‐esteem of peer supporters, and also impact positively on perceptions of bullying in the school; but impact on actual experiences of bullying is less clear, and there may be problems with the acceptance and use of such programmes by older students.     

Random‐effects meta‐analysis of correlations: Monte Carlo evaluation of mean estimators

Several authors have cautioned against using Fisher's z‐transformation in random‐effects meta‐analysis of correlations, which seems to perform poorly in some situations, especially with substantial inter‐study heterogeneity. Attributing this performance largely to the direct z‐to‐r transformation (DZRT) of Fisher z results (e.g. point estimate of mean correlation), in a previous paper Hafdahl (2009) proposed point and interval estimators of the mean Pearson r correlation that instead use an integral z‐to‐r transformation (IZRT). The present Monte Carlo study of these IZRT Fisher z estimators includes comparisons with their DZRT counterparts and with estimators based on Pearson r correlations. The IZRT point estimator was usually more accurate and efficient than its DZRT counterpart and comparable to the two Pearson r point estimators – better in some conditions but worse in others. Coverage probability for the IZRT confidence intervals (CIs) was often near nominal, much better than for the DZRT CIs, and comparable to coverage for the Pearson r CIs; every approach's CI fell markedly below nominal in some conditions. The IZRT estimators contradict warnings about Fisher z estimators' poor performance. Recommendations for practising research synthesists are offered, and an Appendix provides computing code to implement the IZRT as in the real‐data example.