Bias in Cross-Sectional Analyses of Longitudinal Mediation: Partial and Complete Mediation Under an Autoregressive Model

Maxwell and Cole (2007) Maxwell, S. E. and Cole, D. A. 2007. Bias in cross-sectional analyses of longitudinal mediation. Psychological Methods, 12: 23–44. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] showed that cross-sectional approaches to mediation typically generate substantially biased estimates of longitudinal parameters in the special case of complete mediation. However, their results did not apply to the more typical case of partial mediation. We extend their previous work by showing that substantial bias can also occur with partial mediation. In particular, cross-sectional analyses can imply the existence of a substantial indirect effect even when the true longitudinal indirect effect is zero. Thus, a variable that is found to be a strong mediator in a cross-sectional analysis may not be a mediator at all in a longitudinal analysis. In addition, we show that very different combinations of longitudinal parameter values can lead to essentially identical cross-sectional correlations, raising serious questions about the interpretability of cross-sectional mediation data. More generally, researchers are encouraged to consider a wide variety of possible mediation models beyond simple cross-sectional models, including but not restricted to autoregressive models of change.     

Linking cognitive and reaching trajectories via intermittent movement control

Theories of decision-making have traditionally been constrained by reaction time data. A limitation of reaction time data, particularly for studying the temporal dynamics of cognitive processing, is that they index only the endpoint of the decision making process. Recently, physical reaching trajectories have been used as proxies for underlying mental trajectories through decision space. We suggest that this approach has been oversimplified: while it is possible for the motor control system to access the current state of the evidence accumulation process, this access is intermittent. Instead, we demonstrate how a model of arm movements that assumes intermittent, not continuous, access to the decision process is sufficient to describe the effects of stimulus quality and viewing time in curved reaching movements.     

Minor Variations in Maze Patterns: II. The Effect upon the Accuracy of the Reproductions of the Maze

After an exam in which the order of question presentation was varied on the basis of pre-established difficulty levels, student perceptions of the test, course, and instructor were compared. Perceptual scores for 68 Ss across nine evaluative factors were analyzed. The hypothesized existence of a primacy/recency halo effect on perceptual bias received partial support. Five of nine factors were significant in the hypothesized direction at the .05 level.     

Gender and Race Achievement Profiles of Black and White Third-Grade Students

The interrelationships between gender, race, and academic achievement levels were examined. Third-grade students (N = 107) were randomly selected from the poulation of a desegregated metropolitan school district in the deep South. The school district provided the researchers with the gender, race, and California Achievement Test (CAT) score of each student. Results showed that, although the average scores for all subjects on all CAT areas exceeded the national third-grade average, females and whites outperformed males and blacks in all 11 academic areas. The results support the Grant-Sleeter (1986) thesis that important information is neglected if race and gender are treated discretely.     

Mechanisms of change in adolescent life satisfaction: A longitudinal analysis

This study explored the psychosocial mechanisms of change associated with differences in levels and linear change of adolescents' global life satisfaction across a 2-year time period. Based on a theoretical model proposed by Evans (1994), this study tested the relations between selected personality (i.e., extraversion and neuroticism) and environmental (stressful life events) variables and global life satisfaction when mediated by internalizing and externalizing problems. The results suggested support for internalizing problems as a mediator of the relationship of personality and environmental variables with life satisfaction. Pathways mediated by internalizing problems significantly predicted levels and linear change of life satisfaction across a 2-year time span. Furthermore, pathways mediated by externalizing problems significantly predicted the level but not the linear change of life satisfaction. Thus, behavior problems and their antecedents appear to relate significantly to adolescents' perceptions of their quality of life. Implications for adolescent mental health promotion were discussed.     

A Rigorous Test of the Fit of the Circumplex Model to Big Five Personality Data: Theoretical and Methodological Issues and Two Large Sample Empirical Tests

Our objective was to apply the rigorous test developed by Browne (1992) to determine whether the circumplex model fits Big Five personality data. This test has yet to be applied to personality data. Another objective was to determine whether blended items explained correlations among the Big Five traits. We used two working adult samples, the Eugene-Springfield Community Sample and the Professional Worker Career Experience Survey. Fit to the circumplex was tested via Browne's (1992) procedure. Circumplexes were graphed to identify items with loadings on multiple traits (blended items), and to determine whether removing these items changed five-factor model (FFM) trait intercorrelations. In both samples, the circumplex structure fit the FFM traits well. Each sample had items with dual-factor loadings (8 items in the first sample, 21 in the second). Removing blended items had little effect on construct-level intercorrelations among FFM traits. We conclude that rigorous tests show that the fit of personality data to the circumplex model is good. This finding means the circumplex model is competitive with the factor model in understanding the organization of personality traits. The circumplex structure also provides a theoretically and empirically sound rationale for evaluating intercorrelations among FFM traits. Even after eliminating blended items, FFM personality traits remained correlated.     

Extraversion,Neuroticism, and Face-Name Learning

Previous research has attempted to relate personality traits to paired-associate learning. We tested name recall as a function of extraversion and neuroticism (as assessed by the Eysenck Personality Inventory) and task difficulty. Face photographs were paired with one of three levels of information: names only (an easy task); names and occupations; or names, occupations, and interests (a difficult task). On the easy and difficult tasks, extraverted subjects recalled more names than did subjects scoring at the median or below on that trait. Contrary to expectations, subjects scoring high on neuroticism recalled more names than did subjects scoring low on that trait. Neither trait was significantly related to recall on the moderately difficult task. There was no interaction between traits for name recall, but there was for interests: Neurotic introverts were significantly impaired at recalling interests, whereas the other subjects recalled interests better than names. These findings thus differ from those of paired-associate learning tasks using words and nonsense syllables.     

The Stability of Peer Sociometric Ratings Across Ecological Settings

Although children's peer relations extend beyond the classroom, researchers have focused almost exclusively on evaluting sociometric status within the school setting. In the present study, a roster-and-rating method was used to assess the relationship between the sociometric status of 20 fifth-grade students in the classroom and in adult supervised activity groups outside of school. In addition, the 6-month stability of peer sociometric ratings in school was assessed. The correlational results showed that a child's sociometric standing in the classroom was a strong predictor of his or her standing in outside groups, and that the 6-month stability of peer sociometric ratings at school was quite high. The results are encouraging for researchers who use classroom sociometric ratings as global indices of peer relations.