More power to you: Simple power calculations for treatment effects with one degree of freedom

Although numerous computer programs for statistical power analysis are available, power is an under-used aspect of experimental analysis, perhaps because of the perceived difficulty of performing the necessary calculations or because existing computer software can be expensive or complicated to learn. For single-degree-of-freedom tests, however, it is possible to calculate power in a straightforward manner, using thet distribution. Because these calculations are based ont, they use easily understood and readily available quantities. These calculations can be performed with a desk calculator; we also present a simple-to-use program calledMorePower that will perform the necessary calculations. The straightforward nature of the calculations potentially will enable more researchers to consider issues of power when planning and reporting their experiments.     

Volume Contents

Volume Contents

Volume Contents     

Maternal depression and the timing of mother–child dialogue

Turn-taking in dialogue is an essential part of communication and early language experience. The prevalence of utterances and the timing of responses in dialogue were examined at 14 and 36 months of age in 104 mother–child dyads from the Early Head Start Research and Evaluation Project (EHSREP). Mothers varied in their level of depression risk (measured with the Center for Epidemiological Studies-Depression scale; CES-D). Although maternal utterance rate did not vary significantly across any factors, the latency of mothers' responses to their children decreased with development (12 ms/month) and was significantly related to that of their own children (i.e., slow-responding children had slow-responding mothers). Mothers with higher levels of depressive symptoms were 11% slower in responding to their children than mothers with low depression risk, suggesting that the interactive timing of speech to children may be particularly sensitive to maternal depression, modifying the contingent properties of children's early language experience.     

A PRACTICAL STRATEGY FOR ONGOING REINFORCER ASSESSMENT

There is a need for practical methods of reinforcer assessment that systematically track ongoing changes in clients' preferences. In this study, the effects of a time-efficient reinforcer assessment package were evaluated in a multiple baseline across 3 preschoolers with autism, comparing individualized item selections by experienced teachers with children's presession preferences for items of various sensory qualities. Systematic assessment of children's reinforcers for correct responding virtually eliminated nontargeted maladaptive behaviors, as well as yielding expected improvements in accuracy. The powerful side-effects of potent reinforcers underline the importance of increased attention to reinforcer assessment in research and practice.     

AN EVALUATION OF LABELING-THEN-DOING WITH MODERATELY HANDICAPPED PERSONS: ACQUISITION AND GENERALIZATION WITH COMPLEX TASKS

We conducted two experiments in which moderately mentally retarded persons were trained first to label and then to enter characters into a computer, calculator, or checkbook (label-then-do) within a multiple baseline design. In Experiment 1, 5 young adults were trained to enter statistical programs into computers in an office setting. Following training, all subjects' use of verbal labels and key-entry skills generalized across tasks (programs) and settings (offices and computer terminals). In Experiment 2, 3 junior high school students were trained with self-labeling procedures to complete a key-entry task and to balance a checkbook. The performance of all students generalized across tasks and settings, and the use of labels generalized for 2 of the students. Results are discussed relative to mediated generalization and to establishing verbal control over behavior.     

A longitudinal study of job loss in relation to the grief process

This study extended a previous assessment of the applicability of the grief process to job-loss, using a longitudinal sample. A sample of 38 unemployed men were interviewed shortly after job loss (t₁), and at four times over the following year (t₂–t₅), using a structured interview, a personal scaling technique [PQRST: Mulhall (1978), Manual for Personal Questionnaire Scaling Technique. NFER], and standard questionnaires of attachment to the former job, anxiety and depression. Of the sample, 24% fulfilled a criterion for a grief-like response at t₁. Factor analysis of the PQRST showed evidence for a general grief factor. A composite grief score from the interview was associated with two measures of job attachment (at t₁), and with questionnaire measures of depression and anxiety at t₁–t₁. There was a gradual decline over time in the grief reaction.     

Midlife Care Givers: Effectiveness of a Psychoeducational Intervention for Midlife Adults With Parent-Care Responsibilities

The purpose of this study was to develop, implement, and evaluate a psychoeducational group intervention that addressed the needs of adult children caring for aging parents. The intervention consisted of four 2-hour sessions and included 70 care givers, 54 to 72 years of age, who were currently caring for a parent 60 years of age or older. A delayed-treatment, control-group design with follow-up after a 4-week interval was used to study three primary variables identified through an extensive literature review as essential for care givers. These included knowledge, care giver burden, and skill development. Skill development did not change following participation, nor did care giver burden variables measured. Significant increases were found at the .05 level for knowledge, overall coping resources, and self disclosure following group participation.     

Psychological distress in the local hillsborough or ‘host’ community following the Hillsborough football stadium diaster

This paper describes levels of psychological distress and accounts of disaster among the local host community following the Hillsborough Football Stadium disaster. Thirty-two participants were interviewed 4–6 months after the event. Rates of psychological distress symptoms were high in the sample as measured by PTSD (DSM III criteria), Impact of Events Scale (IES) and the General Health Questionnaire (GHQ-28). The study also explores the relationships between levels of exposure, levels of distress and participants' accounts of the disaster. Implications for community outreach projects after disasters are discussed.     

The role of relational similarity in young children’s use of a scale model

The role of relational similarity in 3-year-old children’s understanding of the relation between a scale model and the space it represents was investigated in two studies. Relational similarity was manipulated by arranging the objects within the two spaces in either the same or different configurations; thus, the internal relations among the objects were either identical or very different. The pattern of results across studies revealed that multiple factors interacted to determine the children’s appreciation of the higher-level model–room relation. When other information about the model–room relation was provided via explicit instructions (Experiment 1), relational similarity did not affect performance. However, relational similarity did have a significant effect on performance when only minimal information regarding the model–room relation was given (Experiment 2). These results established that the children were sensitive to the relations among the objects within each space, as well as to whether those relations were similar across spaces. Furthermore, the results indicated that successful performance was supported by appreciation of the higher-level model–room relation, not merely the detection of individual object correspondences.     

Cohesion and power in the families of children involved in bully/victim problems at school

The dimensions of Power and Cohesion have been found to be useful in describing family systems. They may also be predictive of children who will bully others or be victimized themselves. A sample of 20 bullies, 20 victims, 20 bully/victims, and 20 control children were selected from three middle schools via a system of peer nominations. These children then completed a version of the Family System Test (FAST) to establish how they perceived their families on the dimensions of Power and Cohesion. The four subgroups showed characteristic differences on the FAST plots, which are discussed. Future use of the FAST test in examining the link between perceived family structure and peer relationships seems warranted.