Average Weighted Effect Size Research Articles

Alliance in couple and family therapy.

Couple and family therapy (CFT) is challenging because multiple interacting working alliances develop simultaneously and are heavily influenced by preexisting family dynamics. An original meta-analysis of 24 published CFT alliance-retention/outcome studies (k = 17 family and 7 couple studies; N = 1,416 clients) showed a weighted aggregate r = .26, z = 8.13 (p < .005); 95% CI = .33, .20. This small-to-medium effect size is almost identical to that reported for individual adult psychotherapy (Horvath, Del Re, Flückiger, & Symonds, this issue, pp. 9-16). Analysis of the 17 family studies (n = 1,081 clients) showed a similar average weighted effect size (r = .24; z = 6.55, p < .005; 95% CI = .30, .16), whereas the analysis of the 7 couple therapy studies (n = 335 clients) indicated r = .37; z = 6.16, p < .005; 95% CI = .48, .25. Tests of the null hypothesis of homogeneity suggested unexplained variability in the alliance-outcome association in both treatment formats. In this article we also summarize the most widely used alliance measures used in CFT research, provide an extended clinical example, and describe patient contributions to the developing alliance. Although few moderator or mediator studies have been conducted, the literature points to three important alliance-related phenomena in CFT: the frequency of "split" or "unbalanced" alliances, the importance of ensuring safety, and the need to foster a strong within-family sense of purpose about the purpose, goals, and value of conjoint treatment. We conclude with a series of therapeutic practices predicated on the research evidence.

Cognitive Strategy Instruction for Improving Expository Text Comprehension of Students with Learning Disabilities: The Quality of Evidence

Educators have widely used cognitive strategy instruction to address reading comprehension deficits evidenced by students with learning disabilities. However, no one has yet conducted a review of the quality of this literature. This review applies the quality indicators advocated by Gersten et al. (2005) and Horner et al. (2005) to evaluate the quality of published group and single-subject design studies that support cognitive strategy instruction. The authors analyzed 18 group studies and 7 single-subject design studies and calculated average weighted effect sizes and percentage of nonoverlapping data (PND). Only group design studies met the criteria for cognitive strategy instruction as an evidence-based practice. The authors also discuss implications for future research and practice.

School Counseling Outcome: A Meta‐Analytic Examination of Interventions

The effectiveness of school counseling interventions is important in this era of evidence‐based practices. In this study, Meta‐Analysis 1 involved treatment‐control comparisons and Meta‐Analysis 2 involved pretest‐posttest differences. The overall average weighted effect size for school counseling interventions was .30. The study examined whether pertinent moderator variables influenced effect sizes. The pretest‐posttest effect size was not significant, so moderator analyses were conducted on treatment‐control comparisons. Analyses of moderator variables indicated school counseling program activities or interventions varied in effectiveness.

The Effects of Parent Participation on Child Psychotherapy Outcome: A Meta-Analytic Review

Forty-eight child psychotherapy outcome studies offering direct comparisons of an individual child treatment group to a combined parent–child/family therapy treatment group were included in this meta-analytic review. Results indicate that combined treatments produced a moderate effect beyond the outcomes achieved by individual child treatments, with an average weighted effect size that is within the medium range (d = 0.27). Moderator analysis indicated that, compared to non-cognitive-behavioral individual child treatments, cognitive-behavioral individual child treatments were closer in effectiveness to the overall more effective treatments that included parent participation. Results suggest that including parents in the psychotherapeutic treatment of children adds benefits beyond the outcomes achieved by individual child therapies. More research is needed on factors affecting parents' engagement and consistent participation in child psychotherapy treatment and on clinician's utilization of parents as therapy coparticipants.

Estimating fitness consequences of dispersal: a road to ‘know‐where’? Non‐random dispersal and the underestimation of dispersers’ fitness

1. Many studies investigating fitness correlates of dispersal in vertebrates report dispersers to have lower fitness than philopatric individuals. However, if dispersers are more likely to produce dispersing young or are more likely to disperse again in the next year(s) than philopatric individuals, there is a risk that fitness estimates based on local adult survival and local recruitment will be underestimated for dispersers. 2. We review the available empirical evidence on parent-offspring resemblance and individual lifelong consistency in dispersal behaviour, and relate these studies to recent studies of fitness correlates of dispersal in vertebrates. 3. Of the 12 studies testing directly for parent-offspring resemblance in dispersal propensity, five report a significant resemblance. The average effect size (r) of parent-offspring resemblance in dispersal was 0.15 [95% confidence interval (CI) = 0.07-0.22], with no difference between the sexes (average weighted effect size of 0.12 (0.08-0.16) and 0.16 (0.11-0.20) for females and males, respectively). Only three studies report data on within-individual consistency in dispersal propensity, of which two suggest dispersers to be more likely to disperse again. 4. To assess the magnitude of fitness underestimation expected for dispersing individuals depending on the heritability of dispersal distance and study area size, we used a simulation approach. Even when study area size is 10 times the mean dispersal distance, local recruitment per breeding event may be underestimated by 4-10%, generating a potential difference of 4-60% in average lifetime production of recruits between dispersing and philopatric individuals, with larger differences in long-lived species. 5. Estimates of both fitness correlates of dispersal and parent-offspring resemblance or within-individual consistency in dispersal behaviour have been reported for 11 species. Although some comparisons suggest genuine differences in fitness components between philopatric and dispersing individuals, others, based on adult and juvenile survival, are open to the alternative explanation of biased fitness estimates. 6. We list three potential ways of reducing the risk of making wrong inferences on biased fitness estimates due to such non-random dispersal behaviour between dispersing and philopatric individuals: (a) diagnosing effects of non-random dispersal, (b) reducing the effects of spatially limited study area and (c) performing controlled experiments.

Marital Quality and Personal Well‐Being: A Meta‐Analysis

This study examines the association between marital quality and personal well‐being using meta‐analytic techniques. Effects from 93 studies were analyzed. The average weighted effect size r was .37 for cross‐sectional and .25 for longitudinal effects. Results indicate that several variables moderate the association between marital quality and personal well‐being, including gender, participants’ marital duration, source of measurement, data collection year, and dependent variable. These results suggest that longitudinal effects are more likely to be uncovered when using standard measurement and that future research should use samples homogenous in marital length. The longitudinal finding that the strength of the association is stronger when personal well‐being is treated as the dependent variable supports previous theorizing.

Therapist Affect Focus and Patient Outcomes in Psychodynamic Psychotherapy: A Meta-Analysis

The authors systematically examined the relationship between therapist facilitation of patient emotional experience/expression and outcome in psychodynamic psychotherapy. Computer and manual searches were conducted for relevant publications, and 10 independent samples of short-term dynamic psychotherapy were included in a meta-analysis. Data analysis included calculation of an overall effect size of the relationship between therapist affect focus and outcome, statistical significance, and test for homogeneity. In addition, moderator analyses were conducted to examine the potential impact of type of outcome construct used and the methodological quality of individual studies. The overall average weighted effect size across all outcome types was statistically significant (r=0.30), and the homogeneity statistic was nonsignificant. Moderator analyses indicated a statistically significant relationship between therapist facilitation of patient emotional experience/expression and outcome when more than one outcome construct was included but not when either a single or an unclear outcome construct was used. There were no significant relationships between methodological quality and the size of the effects, although use of audio- or videotaping for supervision demonstrated a moderate effect. These data indicate that therapist facilitation of patient affective experience/expression is associated with patient improvement over the course of psychodynamic psychotherapy. Although the size of this relationship was not significantly related to methodological quality, results suggest the importance of close supervision of actual techniques through the use of audio- or videotapes. Additionally, results highlight the importance of defining outcome in a multidimensional way to properly assess theoretically relevant effects.

Therapist Affect Focus and Patient Outcomes in Psychodynamic Psychotherapy: A Meta-Analysis

Objective: The authors systematically examined the relationship between therapist facilitation of patient emotional experience/expression and outcome in psychodynamic psychotherapy. Method: Computer and manual searches were conducted for relevant publications, and 10 independent samples of short-term dynamic psychotherapy were included in a meta-analysis. Data analysis included calculation of an overall effect size of the relationship between therapist affect focus and outcome, statistical significance, and test for homogeneity. In addition, moderator analyses were conducted to examine the potential impact of type of outcome construct used and the methodological quality of individual studies. Results: The overall average weighted effect size across all outcome types was statistically significant (r=0.30), and the homogeneity statistic was nonsignificant. Moderator analyses indicated a statistically significant relationship between therapist facilitation of patient emotional experience/expression and outcome when more than one outcome construct was included but not when either a single or an unclear outcome construct was used. There were no significant relationships between methodological quality and the size of the effects, although use of audio- or videotaping for supervision demonstrated a moderate effect. Conclusions: These data indicate that therapist facilitation of patient affective experience/expression is associated with patient improvement over the course of psychodynamic psychotherapy. Although the size of this relationship was not significantly related to methodological quality, results suggest the importance of close supervision of actual techniques through the use of audio- or videotapes. Additionally, results highlight the importance of defining outcome in a multidimensional way to properly assess theoretically relevant effects.

A meta-analysis of writing instruction for adolescent students.

There is considerable concern that the majority of adolescents do not develop the competence in writing they need to be successful in school, the workplace, or their personal lives. A common explanation for why youngsters do not write well is that schools do not do a good job of teaching this complex skill. In an effort to identify effective instructional practices for teaching writing to adolescents, the authors conducted a meta-analysis of the writing intervention literature (Grades 4-12), focusing their efforts on experimental and quasi-experimental studies. They located 123 documents that yielded 154 effect sizes for quality of writing. The authors calculated an average weighted effect size (presented in parentheses) for the following 11 interventions: strategy instruction (0.82), summarization (0.82), peer assistance (0.75), setting product goals (0.70), word processing (0.55), sentence combining (0.50), inquiry (0.32), prewriting activities (0.32), process writing approach (0.32), study of models (0.25), grammar instruction (- 0.32).

The Effectiveness of Sexual Offender Treatment for Juveniles as Measured by Recidivism: A Meta-analysis

Published and unpublished data from nine studies on juvenile sexual offender treatment effectiveness were summarized by meta-analysis (N=2986, 2604 known male). Recidivism rates for sexual, non-sexual violent, non-sexual non-violent crimes, and unspecified non-sexual were as follows: 12.53%, 24.73%, 28.51%, and 20.40%, respectively, based on an average 59-month follow-up period. Four included studies contained a control group (n=2288) and five studies included a comparison treatment group (n=698). An average weighted effect size of 0.43 (CI=0.33-0.55) was obtained, indicating a statistically significant effect of treatment on sexual recidivism. However, individual study characteristics (e.g., handling of dropouts and non-equivalent follow-up periods between treatment groups) suggest that results should be interpreted with caution. A comparison of odds ratios by quality of study design indicated that higher quality designs yielded better effect sizes, though the difference between groups was not significant.

The Effectiveness of Sexual Offender Treatment for Juveniles as Measured by Recidivism: A Meta-analysis

Published and unpublished data from nine studies on juvenile sexual offender treatment effectiveness were summarized by meta-analysis (N=2986, 2604 known male). Recidivism rates for sexual, non-sexual violent, non-sexual non-violent crimes, and unspecified non-sexual were as follows: 12.53%, 24.73%, 28.51%, and 20.40%, respectively, based on an average 59-month follow-up period. Four included studies contained a control group (n=2288) and five studies included a comparison treatment group (n=698). An average weighted effect size of 0.43 (CI=0.33-0.55) was obtained, indicating a statistically significant effect of treatment on sexual recidivism. However, individual study characteristics (e.g., handling of dropouts and non-equivalent follow-up periods between treatment groups) suggest that results should be interpreted with caution. A comparison of odds ratios by quality of study design indicated that higher quality designs yielded better effect sizes, though the difference between groups was not significant.

Effect of practice on standardised learning outcomes in simulation-based medical education

This report synthesises a subset of 31 journal articles on high-fidelity simulation-based medical education containing 32 research studies drawn from a larger qualitative review published previously. These studies were selected because they present adequate data to allow for quantitative synthesis. We hypothesised an association between hours of practice in simulation-based medical education and standardised learning outcomes measured as weighted effect sizes. Journal articles were screened using 5 exclusion and inclusion criteria. Response data were extracted and 3 judges independently coded each study. Learning outcomes were standardised using a common metric, the average weighted effect size (AWES), due to the heterogeneity of response measures in individual studies. anova was used to evaluate AWES differences due to hours of practice on a high-fidelity medical simulator cast in 5 categories. The eta squared (eta2) statistic was used to assess the association between AWES and simulator practice hours. There is a strong association (eta2=0.46) between hours of practice on high-fidelity medical simulators and standardised learning outcomes. The association approximates a dose-response relationship. Hours of high-fidelity simulator practice have a positive, functional relationship with standardised learning outcomes in medical education. More rigorous research methods and more stringent journal editorial policies are needed to advance this field of medical education research.

A Meta-Analysis of the Effect of Hospital-Based Case Management on Hospital Length-of-Stay and Readmission

Although many hospital-based case management (CM) interventions have been studied, there is little work summarizing the effectiveness of these studies. The purpose of this study was to investigate the effect of hospital-based CM compared with usual care on length of hospital stay and readmission rate. A meta-analytic method was employed to analyze the effect sizes of CM intervention on outcomes. Eligible studies were retrieved using computerized database searches, footnote chasing, and contact with content experts. The authors reviewed the final 12 studies, and the effect size, 95% confidence interval (CI), sensitivity, homogeneity, and publication bias were analyzed. The overall average weighted effect size on length of stay (LOS) was 0.094 with a 95% CI of -0.032 to 0.220. The overall odds ratio for readmission was 0.87 with a 95% CI of 0.69 to 1.04. Overall, hospital-based CM interventions were not significantly effective in reducing LOS and readmissions. However, CM for patients with heart failure (effect size of 0.241 with a 95% CI of 0.012 to 0.470) was significantly effective in reducing LOS, although it was not effective for stroke patients (effect size of -0.226 with a 95% CI of -0.542 to 0.089) and frail elders (effect size of 0.126 with a 95% CI of -0.073 to 0.324). Analysis indicated that in this meta-analysis publication bias was unlikely. The findings of this meta-analysis demonstrate a 6% decrease in readmission rate for patients who received hospital-based CM interventions. Further meta-analytic studies are needed to investigate the effectiveness of CM on other outcomes.

Outcomes for women with co-occurring disorders and trauma: Program-level effects

Program-level effects at 6 months are reported from meta-analysis of a nine-site quasi-experimental study of comprehensive, integrated, trauma-informed, and consumer-involved services for women who have mental health problems, substance use disorders, and who have experienced interpersonal violence. The average weighted effect size is significant for the treatment condition for improved post-traumatic symptoms ( p < 0.02), drug use problem severity ( p < 0.02), and nearly significant for mental health symptoms ( p < 0.06). There is significant heterogeneity in effect sizes across sites. Program-level variables were examined in an effort to explain this heterogeneity. The findings indicate that sites which provided significantly more integrated counseling produced more favorable results in mental health symptoms ( p < 0.01) and both alcohol ( p < 0.001) and drug use problem severity ( p < 0.001). The same trend is observable for reductions in post-traumatic stress symptoms, although the difference does not attain statistical significance.

Preoperative partitioning of pulmonary vascular resistance correlates with early outcome after thromboendarterectomy for chronic thromboembolic pulmonary hypertension

Although there have been numerous investigations into the relationship between gender and bargaining competitiveness over the past several decades, few conclusions have been reached. The results of 62 research reports on the relationship between gender and competitive behavior in dyadic bargaining interactions were examined by meta-analytic review. The average weighted effect size indicated that women appear to behave more cooperatively in negotiations than men, but this difference is slight. Results suggest that constraints on negotiators (imposed by abstract bargaining paradigms and restrictions on communication) lessen gender differences in negotiation behavior. Women were significantly more competitive than men when competing against an opponent who pursued a “tit-for-tat” bargaining strategy.

What is the impact of genetic counselling in women at increased risk of developing hereditary breast cancer? A meta-analytic review

Meta-analytic methods were used to determine the impact of genetic counselling on women with a family history of breast cancer. Published studies with prospective designs and randomized controlled trials were included in the review, and the psychological outcomes assessed were generalized psychological distress, generalized anxiety, depression, and breast cancer anxiety. Other outcomes investigated were the accuracy of perceived risk of developing breast cancer, breast cancer genetics knowledge and breast cancer screening uptake. A meta-analysis was performed to estimate effect size, where sufficient data were available. A total of 12 studies, most of which measured several outcomes, met at least one of the inclusion criteria. A sufficiently large number of studies were available to assess the magnitude of effects on three outcomes: generalized psychological distress, generalized anxiety and accuracy of perceived risk of developing breast cancer. The quantitative synthesis showed that genetic counselling leads to statistically significant decreases in generalized anxiety, with an average weighted effect sizes of r=−0.17 ( p<0.01). In contrast, the reduction in psychological distress exhibited a trend towards statistical significance only, with r=−0.074 ( p=0.052). The impact of genetic counselling on the accuracy of perceived risk was associated with an effect size of r=0.56 ( p<0.01). Thus in this meta-analysis, we demonstrated the efficacy of genetic counselling in meeting two of its objectives: reducing women's anxiety levels and improving the accuracy of their perceived risk. This review highlighted that most research so far focused on generalized distress and anxiety and accuracy of perceived risk, to the exclusion of other, perhaps equally important, types of outcomes. Future studies are likely to lead to more comprehensive assessments if additional emotional, cognitive and behavioural outcomes are included in the assessment.

Interparental Conflict and Parenting Behaviors: A Meta‐Analytic Review

The purpose of this study is to examine the association between interparental conflict and parenting using meta‐analytic review techniques. One‐hundred and thirty‐eight effect sizes from 39 studies are analyzed. The overall average weighted effect size is −.62, indicating a moderate association and support for the spillover hypothesis. The parenting behaviors most impacted by interparental conflict are harsh discipline and parental acceptance. Several moderating effects for subject and method characteristics are significant.

Gender and Negotiator Competitiveness: A Meta-analysis

Although there have been numerous investigations into the relationship between gender and bargaining competitiveness over the past several decades, few conclusions have been reached. The results of 62 research reports on the relationship between gender and competitive behavior in dyadic bargaining interactions were examined by meta-analytic review. The average weighted effect size indicated that women appear to behave more cooperatively in negotiations than men, but this difference is slight. Results suggest that constraints on negotiators (imposed by abstract bargaining paradigms and restrictions on communication) lessen gender differences in negotiation behavior. Women were significantly more competitive than men when competing against an opponent who pursued a “tit-for-tat” bargaining strategy.

Effects of Multigrade and Multi-Age Classes Reconsidered

In response to “Cognitive and Noncognitive Effects of Multigrade and Multi-Age Classes: A Best-Evidence Synthesis” ( Veenman, 1995 ), Mason and Burns (1996) report that their research and review of the literature has led them to conclude that multigrade classes have a slightly negative effect on student achievement. They argue, moreover, that multigrade classes generally have better students and perhaps better teachers and that this selection bias masks the negative effects of less effective instruction in multigrade classes. In this rejoinder, a reanalysis, based on meta-analytic procedures, of the available multigrade and multi-age studies shows the average weighted effect sizes to be essentially zero or close to zero. For all analyses, the confidence intervals around the average effect sizes included zero. These results provide little support for the assumption that the quality of instruction in multigrade classes is lower than in single-grade classes. Between-study differences revealed that favorable conditions for classroom instruction, the country of publication, the locality and socioeconomic status of the school, the grade level of the students, and the number of years spent in multigrade classes need the attention of investigators in future research into the effects of multigrade classes.

Effects of Multigrade and Multi-Age Classes Reconsidered

In response to “Cognitive and Noncognitive Effects of Multigrade and Multi-Age Classes: A Best-Evidence Synthesis” (Veenman, 1995), Mason and Burns (1996) report that their research and review of the literature has led them to conclude that multigrade classes have a slightly negative effect on student achievement. They argue, moreover, that multigrade classes generally have better students and perhaps better teachers and that this selection bias masks the negative effects of less effective instruction in multigrade classes. In this rejoinder, a reanalysis, based on meta-analytic procedures, of the available multigrade and multi-age studies shows the average weighted effect sizes to be essentially zero or close to zero. For all analyses, the confidence intervals around the average effect sizes included zero. These results provide little support for the assumption that the quality of instruction in multigrade classes is lower than in single-grade classes. Between-study differences revealed that favorable conditions for classroom instruction, the country of publication, the locality and socioeconomic status of the school, the grade level of the students, and the number of years spent in multigrade classes need the attention of investigators in future research into the effects of multigrade classes.