Book excerpt: And examples -- References -- Construct validity in physical activity research / Matthew T. Mahar and David A. Rowe -- Definitional stage -- Confirmatory stage -- Theory-testing stage -- Summary -- References -- Physical activity data : odd distributions yield strange answers / Jerry R. Thomas and Katherine T. Thomas -- Overview of the general linear model and rank-order procedures -- Determining whether data are normally distributed -- Application of rank-order procedures -- Data distributions and correlation -- Extensions of GLM rank-order statistical procedures -- Summary -- Endnote -- References -- Equating and linking of physical activity questionnaires / Weimo Zhu -- What is scale equating? -- Equating methods -- Practical issues of scale equating -- Remaining challenges and future research directions -- Summary -- References.