Using generalized additive (mixed) models to analyze single case designs

This article shows how to apply generalized additive models and generalized additive mixed models to single-case design data. These models excel at detecting the functional form between two variables (often called trend), that is, whether trend exists, and if it does, what its shape is (e.g., linear and nonlinear). In many respects, however, these models are also an ideal vehicle for analyzing single-case designs because they can consider level, trend, variability, overlap, immediacy of effect, and phase consistency that single-case design researchers examine when interpreting a functional relation. We show how these models can be implemented in a wide variety of ways to test whether treatment is effective, whether cases differ from each other, whether treatment effects vary over cases, and whether trend varies over cases. We illustrate diagnostic statistics and graphs, and we discuss overdispersion of data in detail, with examples of quasibinomial models for overdispersed data, including how to compute dispersion and quasi-AIC fit indices in generalized additive models. We show how generalized additive mixed models can be used to estimate autoregressive models and random effects and discuss the limitations of the mixed models compared to generalized additive models. We provide extensive annotated syntax for doing all these analyses in the free computer program R.     

Use of video observation and motor imagery on jumping performance in national rhythmic gymnastics athletes

The aim of this study was to evaluate whether a mental training protocol could improve gymnastic jumping performance. Seventy-two rhythmic gymnasts were randomly divided into an experimental and control group. At baseline, experimental group completed the Movement Imagery Questionnaire Revised (MIQ-R) to assess the gymnast ability to generate movement imagery. A repeated measures design was used to compare two different types of training aimed at improving jumping performance: (a) video observation and PETTLEP mental training associated with physical practice, for the experimental group, and (b) physical practice alone for the control group. Before and after six weeks of training, their jumping performance was measured using the Hopping Test (HT), Drop Jump (DJ), and Counter Movement Jump (CMJ). Results revealed differences between jumping parameters F(1, 71) = 11.957; p < .01, and between groups F(1, 71) = 10.620; p < .01. In the experimental group there were significant correlations between imagery ability and the post-training Flight Time of the HT, r(34) = −.295, p < .05 and the DJ, r(34) = −.297, p < .05. The application of the protocol described herein was shown to improve jumping performance, thereby preserving the elite athlete’s energy for other tasks.     

Positive beliefs about worry: A psychometric evaluation of the Why Worry-II

Positive beliefs about worry are theorized to maintain excessive and uncontrollable worry, the hallmark of generalized anxiety disorder (GAD; American Psychiatric Association, 2013). The Why Worry-II (WW-II) is a 25-item revised questionnaire designed to measure five positive beliefs about worry. These five beliefs are that worry: (1) facilitates problem solving; (2) enhances motivation; (3) protects against negative emotions; (4) prevents negative outcomes; and (5) reflects a positive personality trait. The main goal of this study was to assess the WW-II’s psychometric properties, including its factor structure. Undergraduate participants (N = 309) completed the WW-II, and measures of worry, depression, anxiety, and positive and negative beliefs about worry. Overall, the results suggest that the five-factor model is a good fit to the data. The WW-II demonstrated excellent internal consistency, good test–retest reliability at six weeks, and evidence of convergent and divergent validity. The WW-II also uniquely predicted worry severity. Overall, our findings suggest that the WW-II has a five-factor structure congruent with theoretical predictions, sound psychometric properties, and a unique relationship to excessive worry. The theoretical and clinical implications of these findings are discussed.     

Italian Adaptation and Confirmatory Factor Analysis of the Full and the Short Form of the Posttraumatic Growth Inventory

This study was designed to adapt and to assess the reliability and factor structure of an Italian translation of the full and short form of the Posttraumatic Growth Inventory. A sample of 1,244 Italian adults who had experienced a range of adverse life events participated in this study. Five models of the underlying structure of the Posttraumatic Growth Inventory were tested via confirmatory factor analyses. Analyses of both the short and full form of the PTGI provided support for the original correlated five-factor structure. Multigroup confirmatory factor analysis supported the invariance of the Posttraumatic Growth Inventory across gender.     

Massage therapy improves the development of HIV-exposed infants living in a low socio-economic,peri-urban community of South Africa

The aim of this study was to assess the effect of massage therapy on the growth and development of infants of HIV-infected mothers in a low socio-economic community in Cape Town. It was a prospective, randomised, controlled intervention trial that included massage therapy and control groups of HIV-infected mothers and their normal birth weight infants who were enrolled in the prevention of mother-to-child transmission (PMTCT) programme. Participants were recruited at the 6-week clinic visit and followed up every 2 weeks until their infants were 9 months of age. Mother–infant pairs in the massage therapy and control groups included 73 and 88 at 6 weeks and 55 and 58 at 9 months, respectively. Mothers in the intervention group were trained to massage their infants for 15 min daily. The socioeconomic status, immunity, relationship with the partner and mental pain of mothers; the infants’ dietary intake, anthropometry and development (Griffiths Mental Development Scales); and haematological and iron status of mothers and infants were assessed at baseline and follow-up. Nine infants (5.3%) were HIV-infected on the HIV DNA PCR test at 6 weeks. Despite significantly higher levels of maternal mental pain, infants in the massage therapy compared to control group scored higher in all five of the Griffiths Scales of Mental Development and significantly higher in the mean quotient (p = 0.002) and mean percentile (p = 0.004) for the hearing and speech scale at 9 months. Based on the mean difference in scores, the massage therapy group showed greater improvement for all five scales compared to the control group. The mean difference in scores was significantly greater for the hearing and speech quotient (21.9 vs. 11.2) (p < 0.03) and the general quotient percentile (19.3 vs. 7.7) (p = 0.03) in the massage therapy compared to the control group. These scales remained significant when adjusting for the relationship with the partner and maternal mental pain. Both groups had lower scores in the performance scale at 9 months although this was significantly worse in the control compared to the massage therapy group when adjusting for maternal CD4 count, anaemia, relationship with the partner and mental pain. There were no significant differences in the anthropometric measurements between the two groups. In conclusion, based on the Griffiths Scales, massage therapy improved the overall development and had a significant effect on the hearing and speech and general quotient of HIV-exposed infants in this study.     

Efficacy of a cognitive-behavioural therapy administered by videoconference for generalized anxiety disorder

IntroductionDelivering psychotherapy by videoconference could considerably extend the accessibility of empirically validated treatments.ObjectiveThe aim of this study was to evaluate the efficacy of a cognitive-behavioural therapy (CBT) for generalized anxiety disorder (GAD), administered via videoconference.MethodFive participants with a primary diagnosis of GAD took part in an experimental multiple baseline case study protocol. The efficacy of the treatment was evaluated using a semi-structured interview, self-report questionnaires, and daily self-monitoring diaries.ResultsThe results demonstrate that overall, participants’ conditions were improved following treatment and they no longer met the diagnostic criteria for GAD in the short-term. Participants’ conditions improved clinically and statistically at each follow-up point, achieving a greater global level of functioning at post-test, as well as at 3-month and 12-month follow-up.ConclusionClinical implications of this new treatment modality and directions for future research are discussed.     

The Faulty Magnitude Detector: Why SNARC‐Like Tasks Cannot Support a Generalized Magnitude System

Do people represent space, time, number, and other conceptual domains using a generalized magnitude system (GMS)? To answer this question, numerous studies have used the spatial‐numerical association of response codes (SNARC) task and its variants. Yet, for a combination of reasons, SNARC‐like effects cannot provide evidence for a GMS, even in principle. Rather, these effects support a broader theory of how people use space metaphorically to scaffold their understanding of myriad non‐spatial domains, whether or not these domains exhibit variation in magnitude.     

纵向数据分析方法

纵向研究方法是心理学研究领域的一种重要方法。近年来,国外在纵向研究数据分析方法上取得了一系列理论和应用上的进展。章对此方法进行了简要的回顾,并重点阐述了最近发展起来的纵向研究的方法：多层线性模型和潜变量增长曲线模型,并在此基础上对几种常用的方法进行了比较。     

In search of average growth: Describing within-year oral reading fluency growth across Grades 1–8

Measures of oral reading fluency (ORF) are perhaps the most often used assessment to monitor student progress as part of a response to intervention (RTI) model. Rates of growth in research and aim lines in practice are used to characterize student growth; in either case, growth is generally defined as linear, increasing at a constant rate. Recent research suggests ORF growth follows a nonlinear trajectory, but limitations related to the datasets used in such studies, composed of only three testing occasions, curtails their ability to examine the true functional form of ORF growth. The purpose of this study was to model within-year ORF growth using up to eight testing occasions for 1448 students in Grades 1 to 8 to assess (a) the average growth trajectory for within-year ORF growth, (b) whether students vary significantly in within-year ORF growth, and (c) the extent to which findings are consistent across grades. Results demonstrated that for Grades 1 to 7, a quadratic growth model fit better than either linear or cubic growth models, and for Grade 8, there was no substantial, stable growth. Findings suggest that the expectation for linear growth currently used in practice may be unrealistic.     

On the statistical and theoretical basis of signal detection theory and extensions: Unequal variance, random coefficient, and mixture models

Basic results for conditional means and variances, as well as distributional results, are used to clarify the similarities and differences between various extensions of signal detection theory (SDT). It is shown that a previously presented motivation for the unequal variance SDT model (varying strength) actually leads to a related, yet distinct, model. The distinction has implications for other extensions of SDT, such as models with criteria that vary over trials. It is shown that a mixture extension of SDT is also consistent with unequal variances, but provides a different interpretation of the results; mixture SDT also offers a way to unify results found across several types of studies.