ANOVA Article Critique
PSY 325 Statistics of Behavioral & Social Sciences (PSI1918A)
ANOVA Article Critique
Analysis of variance, or ANOVA is used in research when there is an independent variable (IV) and can accommodate any number of groups more than one. In this study, researchers used 38 children ages 5-17 with autism and severe behavioral disturbance, to test the cognitive effects of the drug risperidone. For this paper, in the article titled “Cognitive Effects of Risperidone in Children with Autism and Irritable Behavior”, I will address the exploration of the effects of risperidone on cognitive processes in children with autism and irritable behavior, methods used to conduct the research as well as statistical assumptions and limitations in the study.
The authors for this study had a few questions that they wanted answered with the research they conducted. One of the questions being if the drug risperidone would have a positive affect in children previously diagnosed with autism and irritable behavior. In the same sense, would the drug risperidone have an adverse effect in children diagnosed with autism and irritable behavior. For this study, the hypothesis being tested is if risperidone effects the cognitive state of children that fit into that description. Aman, Hollway, McDougle, Scahill, Tierney, McCracken, & Posey (2008) states, “The present study was designed to test whether risperidone has an effect on cognitive performance in children with autism accompanied by serious behavior problems. This was an exploratory comparison, as no data were available with AAPs in children with autism at the time of the trial. The null hypothesis is that there would be no differences between placebo and risperidone.”
Researchers used an array of methods in order to reach an outcome for their research. One method was using a flexible dosage based on certain characteristics of the participant such as weight, time in study, clinical response, and emergence of adverse events. Researchers also used a baseline of four weeks and eight weeks to conduct cognitive assessments for the participants. “This study used an acute, double blind, placebo controlled, parallel groups design. After being assessed at the screen visit, participants who met inclusion criteria for the study were then reassessed with clinical instruments at baseline and weekly for the next 8 weeks. Matched placebo and risperidone were provided by the manufacturer (Janssen Pharmaceutica) in tablet form (Aman, M. G., Hollway, J. A., McDougle, C. J., Scahill, L., Tierney, E., McCracken, J. T., Posey, D. J., 2008).
Reviewing the methods, data and outcome of this study there are a few things I would change. For example, participants and the focus. Although the outcome showed risperidone to have no detrimental effect on cognitive performance, I would have liked to see the study focused on more participants. Out of the 101essentially, only 38 were tested. According to Tanner (2016), “The associated benefit of adding more IVs to the analysis is that the researcher can more accurately reflect the complexity inherent in human behavior. One variable rarely explains behavior in any comprehensive way.” This could also result in a more powerful test. Which brings me to my next point about limitations in this research.
There were several limitations within this study. Researchers were able to come to a basic result of the testing but that did not change the limitations within the study. “This study has several limitations that caution against over-embracing the statistically-significant (and one equivocal) findings. First, given the exploratory nature of this work (there is only one other study of atypical antipsychotics in children with PDDs), we adopted the .05 level for alpha. Had we corrected for multiple comparisons, none of the comparisons would have exceeded alpha. Second, only a minority of our participants were able to perform these tasks. This resulted in (a) small sample sizes and (b) the observation that the testable group had a higher IQ and was older than the untestable group. This indicates that the findings may not be fully representative of what would be observed if all the 101 clinical trial participants were testable (Aman, M. G., Hollway, J. A., McDougle, C. J., Scahill, L., Tierney, E., McCracken, J. T., Posey, D. J., 2008).”
Authors of this study used a number of statistical testing to see what the effects of the risperidone did to cognitive functions in the participants. One of the tests used was The Visuospatial Memory Test also known as the ‘Dot Test’. This test provided researchers with an answer as to whether or not the participants could recall without memorization. Another test used for cognitive function testing was Cancellation Task, which tracked attention span by cancelling a target figure. The Purdue Pegboard Task tracked cognitive functions between the dominant and non-dominant hands, and Classroom Analogue Task tested basic ability related math within the group.
From the research we can conclude that multiple IVs were used. “In the language of statistics, a factor is an independent variable, and a factorial ANOVA is an ANOVA that includes multiple IVs (Tanner, D.,2016).” The authors findings for this study showed that, there was not an adverse effect of the risperidone on children with autism and irritable behavior. “Of the 101 participants in the clinical trial of risperidone vs. placebo, 38 (37.6%) were able to provide valid cognitive measures. Of these 38 participants, 12 (31.6%) were risperidone responders, 8 (21%) were risperidone nonresponders and 18 (47.4%) were randomized to placebo. Of the 63 (62.4%) participants who were unable to complete valid cognitive measures, 22 (34.9%) were risperidone responders, 7 (11.1%) were risperidone non-responders and 34 (54%) were randomized to placebo (Aman, M. G., Hollway, J. A., McDougle, C. J., Scahill, L., Tierney, E., McCracken, J. T., . Posey, D. J., 2008).”
Tanner, D. (2016). Statistics for the Behavioral & Social Sciences (2nd ed.). San Diego, CA: Bridgepoint Education, Inc.
Aman, M. G., Hollway, J. A., McDougle, C. J., Scahill, L., Tierney, E., McCracken, J. T., . . . Posey, D. J. (2008). Cognitive effects of risperidone in children with autism and irritable behavior. Journal of Child and Adolescent Psychopharmacology, 18(3), 227-36. doi:http://dx.doi.org/10.1089/cap.2007.0133. Retrieved from the ProQuest database.