Analyzing age of milestone attainments from daily checklist recordings using SAS/STAT® procedures
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Abstract
The ages at which children first reach developmental milestones like sitting, crawling, or walking display substantial child-to-child variability that may reveal the operation of important developmental processes. Survival analysis (also called event-history analysis) is well suited for such data because it is designed to assess time-situated events characterized by a qualitative change from one discrete state to another (e.g., from not walking to walking). Multiple definitions of state changes are possible and deserve study, but their implementation from daily recordings is computationally intensive. The SAS/STAT® procedure Expand can efficiently convert raw milestone data into a format for analysis with the SAS Lifereg procedure, one of several survival analysis procedures. This report comprises an annotated SAS program for the conversion of multiple daily checklist recordings into variously defined events suitable for input into an illustrative survival analysis.