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EPID 766: Analysis of Longitudinal Data from ... - NCSU Statistics

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CHAPTER 1 Epid <strong>766</strong>, D. Zhang<br />

Example 3: Epileptic seizure counts <strong>from</strong> progabide trial<br />

In progabide trial, 59 epileptics were randomly assigned to receive<br />

anti-epileptic treatment (progabide) or placebo. The number <strong>of</strong> seizure<br />

counts was recorded in 4 consecutive 2-week intervals. Age and baseline<br />

seizure counts (for an 8 week period prior to treatment assignment) were<br />

also recorded.<br />

Study objectives:<br />

• Does the treatment work?<br />

• What is the treatment effect adjusting for available covariates?<br />

Features <strong>of</strong> this data set:<br />

1. Outcome is count data, implying Poisson regression.<br />

2. Baseline seizure counts were for 8 weeks, as opposed to 2 weeks for<br />

other seizure counts.<br />

3. Randomization may be taken into account in data analysis.<br />

Graduate Summer Session in Epidemiology Slide 18

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