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Our biostatistics department at Vanderbilt University Medical Center sponsors daily biostatisics 'clinics', 75-minute, open, question-and-answer, bring-us-your-stats-problems sessions. One day a researcher brought us a problem: she and others had given a questionnaire to parents of 78 children. Some of the children suffered from autism spectrum disorders (ASD) and some were 'typically developed'. The questionnaire consisted of 14 questions, each with four possible ordinal responses. Each question sought to measure parenting problems, from 1 ('no problem') to 4 ('severe problem'). Each question, we were told, was asked at two time points approximately 20 weeks apart. Do these data show that this questionnaire can be used as a reliable measure of the problems associated with parenting autistic children?, we were asked. Fourteen questions times two time points times 78 children minus two missing data points yielded 2182 data points. How does one show such a data set graphically? The resultant display (pdf approx. 360k, 11x17 inches) is my attempt at showing the entire data set at the datum level and an explanation of what I think it shows. (Please be aware that at 360kb, that pdf might take a while to download. Of course, it looks best printed out onto paper...) |
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(Note that you can download Adobe's Acrobat Reader free at Adobe's web site (www.adobe.com).) Last update: 17 April 2006 |