Neuropsychological changes in children with cancer: The treatment of missing data in longitudinal studies

Researchers conducting longitudinal studies with children or adults are inevitably confronted with problems of attrition and missing data. Missing data in longitudinal studies is frequently handled by excluding from analyses those cases for whom data are incomplete. This approach to missing data is not optimal. On the one hand, if data are missing at random, then dropping incomplete cases ignores information collected on those cases that could be used to improve estimates of population parameters (e.g., means, variances, covariances, and growth rates) and improve the power of significance tests of statistical hypotheses. On the other hand, if data are not missing at random, then dropping incomplete cases leads to biased parameter estimates and hypothesis tests that may be internally and externally invalid. This study uses three years of follow-up data from a longitudinal investigation of neuropsychological outcomes of cancer in children to demonstrate the problems presented by missing data in repeated measures designs and some solutions. In evaluating potential biasing effects of attrition, the study extends previous research on neuropsychological outcomes in pediatric cancer by inclusion of patients whose disease had relapsed, and by comparison of surviving and nonsurviving patients. Although the data presented have specific relevance to the study of neuropsychological outcome in pediatric cancer, the problems of missing data and the solutions presented are relevant to a wide variety of diseases and conditions of interest to researchers in child and adult neuropsychology.     

Tests of sphericity of normal distributions and the analysis of repeated measures designs

The locally best invariant test statistic for testing sphericity of normal distributions is shown to be a simple function of the Box/Geisser-Greenhouse degrees of freedom correction factor in a repeated measures design. Because of this relationship it provides a more intuitively appealing test of the necessary and sufficient conditions for valid F-tests in repeated measures analysis of variance than the likelihood ratio test. The properties of the two tests are compared and tables of the critical values of the Box/Geisser-Greenhouse correction factor are given.     

BEHAVIORAL TREATMENT OF CAFFEINISM: REDUCING EXCESSIVE COFFEE DRINKING

Excessive coffee drinking can have deleterious effects because of the large amounts of caffeine that are ingested. Caffeine is thought to be addicting, and prolonged and excessive use can lead to caffeinism, a condition that has serious behavioral and physiological side effects. The present study developed and evaluated a treatment program to reduce excessive daily coffee drinking to moderate and presumably safer levels. Three habitual coffee drinkers received individualized changing criterion programs that systematically and gradually reduced their daily caffeine intake. The coffee drinkers were required to self-monitor and plot their daily intake of caffeine. They received monetary prizes for not exceeding the treatment phase criteria and forfeited a portion of their pretreatment deposit when they did. Their coffee drinking decreased from almost nine cups per day (over 1100 mg of caffeine) during baseline to less than three cups per day (less than 343 mg) at the end of treatment or a reduction of 69%. The treatment effect was maintained during a 10-month follow-up, averaging a 67% reduction from baseline. The program appears to be a reasonable method of reducing and then maintaining daily caffeine intake at less harmful levels.     

Effects of serial versus concurrent task sequencing an acquisition, maintenance, and generalization

Effects of serial and concurrent task presentation on skill acquisition, generalization, and maintenance were compared. Two severely retarded females participated. During serial training, items of one response class, tracing, were trained to mastery before those of a second task, vocal imitation. In the concurrent method, training on two different tasks, tracing and vocal imitation, alternated within sessions for fixed periods of time. There were no major differences between the serial and concurrent methods of instruction in the number of steps attained per behavior or in the number of trials required to reach criterion levels of performance. It was found however, that concurrent training resulted in more generalization. Retention results were not consistently related to training method.     

Multiple-probe technique: a variation on the multiple baseline

Multiple-baseline and probe procedures are combined into a “multiple-probe” technique. The technique is designed to provide a thorough analysis of the relationship between an independent variable and the acquisition of a successive-approximation or chain sequence. It provides answers to the following questions: (1) What is the initial level of performance on each step in the training sequence? (2) What happens if sequential opportunities to perform each next step in the sequence are provided before training on that step? (3) What happens when training is applied? (4) What happens to the performance of remaining steps in the sequence as criterion is reached in the course of training each prior step? The technique features: (1) one initial probe of each step in the training sequence, (2) an additional probe of every step after criterion is reached on any training step, and (3) a series of “true” baseline sessions conducted just before the introduction of the independent variable to each training step. Intermittent probes also provide an alternative to continuous baseline measurement, when such measurement during extended multiple baselines (1) may prove reactive, (2) is impractical, and/or (3) a strong a priori assumption of stability can be made.     

TOWARD A METHODOLOGY OF WITHDRAWAL DESIGNS FOR THE ASSESSMENT OF RESPONSE MAINTENANCE

Single-case experimental designs have advanced considerably in the evaluation of functional relationships between interventions and behavior change. The systematic investigation of response maintenance once intervention effects have been demonstrated has, however, received relatively little attention. The lack of research on maintenance may stem in part from the paucity of design options that systematically evaluate factors that contribute to maintenance. The present paper discusses three design options potentially useful for the investigation of response maintenance. These include: (a) the sequential-withdrawal, (b) the partial-withdrawal, and (c) the partial-sequential withdrawal designs. Each design is illustrated and potential limitations are discussed.     

The problem-solving diathesis in depression,hopelessness, and suicide ideation: A longitudinal analysis

The problem-solving deficit (PSD) diathesis-stress model of suicide behavior proposed by Clum, Patsiokas, and Luscomb (1979) and expanded by Schotte and Clum (1982, 1987) was examined in a short-term longitudinal test. The present study assessed the relationship between problem-solving deficits at Time 1—prior to the stressor (a D or F on a midterm examination)—and adjustment at Time 2—after the Stressor. Evidence was found for an additive predictive relationship for stress and problem-solving deficits to Time 2 measures of depressive symptoms, hopelessness, and suicide ideation. Evidence was also found that PSD × Stress interactions uniquely predicted the three criteria. The results of this study were taken as evidence of problem-solving deficits functioning as a diathesis for depression, hopelessness, and suicide ideation.     

多种因素对时间连续阈限的影响

该研究做了两个实验,研究了七个因素——刺激的类型、刺激的复杂度、刺激的强度、刺激的呈现时间、被试对两刺激的判断标准、同一种感觉道的个数、性别——对时间连续阈限的影响.在实验一中,结果表明,刺激的类型、刺激的呈现时间、被试对两刺激的判断标准和同一种感觉道的个数四个因素对时间连续阈限有显著影响,而刺激的复杂度、刺激的强度和性别三个因素对时间连续阈限没有显著影响。在实验二中,结果表明,在影响显著的四个因素之间不存在交互作用。     

Longitudinal changes in term and preterm infant night wakings: The role of caregiver anxious-depression

Changes in infant night waking during the first year of life are associated with individual (e.g., prematurity) and family (e.g., caregiver psychopathology) factors. This study examined the association between infant night waking and caregiver anxious-depressive symptoms during the first year of life in preterm and term infants. We considered between-person differences and within-person changes in caregiver anxious-depressive symptoms in relation to changes in infant night waking from 2- to 9-months. Racially (30.0% Black, 60.4% White, 9.5% multiracial/other) and socioeconomically (40.0% below median household income) diverse caregivers (N = 445) of full term (n = 258) and preterm (n = 187) infants were recruited from hospitals and clinics in two midwestern states. Caregivers completed measures of anxious-depression and their infant's night waking at four sampling periods (2-, 4-, 6-, and 9-months). Infant night wakings declined from 2- to 9-months. Between-person differences were observed, such that caregivers with higher average anxious-depressive symptoms or infants born full term reported more night wakings. Within-person effects of caregiver anxious-depressive symptoms were not significant. Caregiver anxious-depression is closely associated with infant night wakings. By considering a caregiver's average severity of anxious-depression, healthcare providers can more effectively plan infant sleep interventions. If caregiver anxious-depressive symptoms are ameliorated, night wakings may also decrease.