


WWC standards briefs provide quick, clear, and concise
summaries of individual WWC standards. Each two-page
brief offers an informative description and helpful graphics
to clarify key concepts. Two new standards briefs discuss
WWC standards for attrition (344 KB) and baseline equivalence (195 KB).
Attrition (344 KB) (loss of sample) is a common issue in education. This occurs when individuals initially randomly
assigned in a study are not included in the analysis.
Baseline Equivalence (195 KB) refers to the degree to which intervention and comparison groups are similar to each other
at the start of a study (baseline)—particularly, whether the
groups are similar on key observable characteristics that are
expected to influence participant outcomes.