Dale E. Berger

Creativity and the Finding and Solving of Real-World Problems:

Divergent thinking tests have been criticized for their low correlations with real-world performance. The primary objective of this study was to ascertain whether real-world problems are more predictive of creative accomplishments than problems contained in standard divergent thinking tasks. A second objective was to examine the relationship between performance on problem-finding tasks and traditional problem-solving tasks. Four tasks were administered to 77 elementary school students, with a check list of creative activities that was used as a criterion measure. Correlational results indicated that the real-world problem-finding measure was more predictive of creative accomplishments than standard divergent thinking tasks and the real-world problem-solving task. Hierarchical regression analyses indicated that the real-world problem-finding task added significantly to the prediction of creative activities, beyond the prediction from the other tasks.

Growing Pains: The Impact of Disaster-Related and Daily Stressors on the Psychological and Psychosocial Functioning of Youth in Sri Lanka.

Daily stressors may mediate the relation between exposure to disaster-related stressors and psychological and psychosocial distress among youth in disaster-affected countries. A sample of 427 Sri Lankan Sinhalese, Tamil, and Muslim youth (mean age = 14.5) completed a survey with measures of exposure to disaster-related stressors and daily stressors, psychological distress (posttraumatic stress, depression, and anxiety), and psychosocial distress. The results indicated that daily stressors significantly mediated relations between war- and tsunami-related stressors and psychological and psychosocial distress. Some daily stressors not directly related to disaster also predicted functioning. These results point to the need for policies and interventions that focus on reducing proximal daily stressors that are salient to Sri Lankan youth exposed to disasters.

Evaluation of an Interactive Tutorial for Teaching the Central Limit Theorem

In this article, we present an evaluation of a Web-based, interactive tutorial used to present the sampling distribution of the mean. The tutorial allows students to draw samples and explore the shapes of sampling distributions for several sample sizes. To evaluate the effectiveness of the tutorial, 111 students enrolled in statistics or research methods courses used either the interactive tutorial or attended a lecture and a demonstration on the sampling distribution of the mean. Students in both groups improved from pretest to posttest and no statistically significant differences between improvement scores were found between groups. Additionally, students rated the tutorial as easy to use and understand. In this study, we provide evidence that an Internet tutorial can be comparable in effectiveness to standard lecture or demonstration techniques.

Evaluation of a Juvenile Diversion Program Using Multiple Lines of Evidence

The evaluation of a juvenile diversion program was approached through the development of multiple lines of evidence bearing on each of the two major program goals: providing a community-based alternative for arrested juveniles who otherwise would have been referred to the juvenile justice system and reducing juvenile delinquency. Convergent results from various measures, research designs, and data stratifications indicated that the program had little success in decreasing referrals to the juvenile justice system but produced a positive delinquency reduction effect (concentrated among less serious offenders). These results are discussed in terms of (1) their significance for the diversion program and (2) the nature of the multiple methodology that produced them.

Cognitive Mode and Asymmetry in Cerebral Functioning

Male graduate students from the fields of sculpture, psychology, and law were used to test the assumption that an individuals cognitive mode (verbal-analytic vs. spatial-holistic) is related to actual laterality in cerebral functioning. A measure of asymmetry of cognitive mode for each student, based on relative performance on three verbal-analytic tests compared to three spatial-holistic tests, successfully discriminated occupational groups. Laterality in cerebral functioning was indexed by relative reaction times to discriminate visual stimuli presented unilaterally to the left or right hemisphere. Reaction times to discriminate faces were less for the right hemisphere, while letters were discriminated faster by the left hemisphere. However, measures of cerebral laterality were not related to occupational group membership nor to asymmetry of cognitive mode. Asymmetry in performance on tests of cognitive mode may reflect an individuals general approach to problem solving, but is not closely related to laterality in cerebral functioning.

Effectiveness of Computer-Assisted Instruction in Statistics A Meta-Analysis

Although previous meta-analyses have documented the efficacy of computer-assisted statistics instruction, the current study examined a range of specific features that presumably influence its effectiveness, such as the level of learner engagement, learner control, and the nature of feedback. In 45 experimental studies with a control condition, computer-assisted statistics instruction provided a meaningful average performance advantage (d = 0.33). Because of great methodological heterogeneity among the studies, the authors employed a conservative but appropriate mixed effects model to examine potential moderator effects. The authors’ analyses revealed three statistically significant findings. Larger effects were reported in studies in which treatment groups received more instructional time than control groups, in studies that recruited graduate students as participants, and in studies employing an embedded assessment. A newly developed second order standardized mean effect size, d diff , reveals that additional study characteristics may serve as meaningful moderators. Tight experimental control is needed to assess the importance of specific instructional features in computer-assisted statistics instruction.

Examination stress as an ecological inducer of cortisol and psychological responses to stress in undergraduate students

The purpose of the present study was to investigate basic methodological issues related to the usage of an examination stress protocol in studies of psychoneuroendocrinology. In the present study, 57 undergraduate students served as participants. All subjects provided salivary samples and completed psychological inventories during a low examination stress period and again during a high examination stress period. Salivary samples were analyzed for cortisol. Three major findings were observed. First, the examination stress protocol proved to be an effective trigger of elevations in both psychological measures of stress and in cortisol levels. Second, sex differences were observed in cortisol levels, such that males showed an elevation in cortisol during the high examination stress session whereas females did not. Finally, no significant correlations were observed between elevations in psychological measures of stress and elevations in cortisol levels. These findings suggest that the examination stress protocol used in the present study effectively elevated both psychological stress and cortisol levels. Furthermore, these findings suggest that there are biological differences in how males and females respond to stress. Finally, no evidence was found to suggest a relationship between psychological and hormonal levels of stress. Together, these findings suggest the need to better define and consider the implications of both the specific measures of stress being used and individual differences in the subject samples in psychoendocrine studies.

Evaluation of an Interactive Tutorial for Teaching Hypothesis Testing Concepts

In this article, we describe and evaluate a Web-based interactive tutorial used to present hypothesis testing concepts. The tutorial includes multiple-choice questions with feedback, an interactive applet that allows students to draw samples and evaluate null hypotheses, and follow-up questions suitable for grading. Students either used the interactive tutorial (n = 15) or completed a standard laboratory assignment (n = 10) covering the same topics. Students who used the tutorial performed better (p =.06) on a quiz than students who completed the standard laboratory, supporting the effectiveness of this freely available online tutorial. A second group of students (n = 112) who did not participate in the assessment overwhelmingly rated the tutorial as easy to use, clear, and useful.

On the inappropriateness of stepwise regression analysis for model building and testing

Dear Editor-in-Chief Pietro E. di Prampero, My colleagues and I recently read the study by Sanada et al. (2007) on the development of prediction models for maximal oxygen uptake ð _ VO2maxÞ. We would like to focus our comments on two particular areas of the study: (1) the use of stepwise regression, and (2) the practical application of the prediction equations. 1. Use of stepwise regression: Stepwise regression allows a computer program to select a small set of the ‘best’ predictors from a larger set of potential predictors (Tabachnick and Fidell 2001). Stepwise procedures should not be used to develop prediction models because this method produces an inflated R-squared (R), inaccurate test of statistical significance, and it does not maximize the theoretical or practical value of the model (Berger 2004; Keppel and Wickens 2004). An essential problem is that estimates of population multiple correlations and tests of statistical significance fail to take into account how many variables were considered in the stepwise analysis. Inflation occurs whether the experimenter selects predictors after looking at the correlations or stepwise regression is used to select the ‘best’ predictors out of a larger set of potential predictors (Cohen et al. 2003). A more realistic estimate of the population multiple correlation is ‘shrunken’ R based on the total number of variables considered. In the Sanada et al. (2007) study where the two strongest predictors from a set of 15 potential predictors produced R of 0.72 with a sample of N = 40, an estimate of the population multiple R based on 15 predictors is the shrunken R of 0.55. Contrary to the conclusions of Sanada et al. (2007) based on their inflated R, their model offers no improvement on models generated in larger studies as shown in their Table 5. Ordinarily a regression formula generated on one sample will produce a smaller R when it is applied to a new sample (Pedhazur 1997). Thus, it is surprising that Sanada et al. (2007) found R to be larger (R = 0.83) in the validation group than in the derivation group (R = 0.72) for which the model was generated. Perhaps this can be explained by large sampling error due to the extremely small sample size (N = 20) for the validation group. In practice, it is always preferable for the investigator to control the order of entry of predictor variables based on theoretical considerations (Berger 2004). This procedure is called ‘‘hierarchical analysis,’’ and it requires the investigator to plan the analysis with care, prior to looking at the data. The double advantage of hierarchical methods over stepwise methods is that there is less capitalization on chance, and careful choice of the order of entry of predictors assures that results such as R added are maximally interpretable (Berger 2004). Kerlinger (1986) stated that, ‘‘... the research problem and the theory behind the problem should determine the order of entry of variables in multiple regression analysis.’’ (p. 545). For example, Malek et al. (2004b, 2005) used hierarchical analysis to develop nonexercise-based M. H. Malek (&) Human Performance Laboratory, Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, 110 Ruth Leverton Hall, Lincoln, NE 68583-0806, USA e-mail: mmalek@unlserve.unl.edu

Validity of VO2max Equations for Aerobically Trained Males and Females

PURPOSE The purpose of this investigation was to cross-validate existing VO2max prediction equations on samples of aerobically trained males and females. METHODS A total of 142 aerobically trained males (mean +/- SD; 39.0 +/- 11.1 yr, N = 93) and females (39.7 +/- 10.1 yr, N = 49) performed a maximal incremental test to determine actual VO2max on a cycle ergometer. The predicted VO2max values from 18 equations (nine for each gender) were compared with actual VO2max by examining the constant error (CE), standard error of estimate (SEE), correlation coefficient (r), and total error (TE). RESULTS The results of this investigation indicated that all of the equations resulted in significant (P < 0.006) CE values ranging from -216 to 1415 mL x min(-1) for the males and 132 to 1037 mL x min(-1) for the females. In addition the SEE, r, and TE values ranged from 266 to 609 mL x min(-1), 0.36 to 0.88, and 317 to 1535 mL x min(-1), respectively. Furthermore, the lowest TE values for the males and females represented 10% and 12% of the mean actual VO2max values, respectively. CONCLUSIONS The results of the analysis indicated that the two equations using age, body weight, and the power output achieved at VO2 as predictor variables had the lowest SEE (7.7-9.8% of actual VO2max) and TE (10-12% of actual VO2max) values and are recommended for estimating VO2max in aerobically trained males and females. The magnitude of the TE values (>or= 20% of actual VO2max) associated with the remaining 16 equations, however, were too large to be of practical value for estimating VO2max.