Writing process studies. Struggling with complexities Looking back, moving forward

This chapter discusses validity parameters for studies on writing processes in a second or foreign language (L2). To that end, Cook and Campbell’s validity framework, which discerns four types of validity, i.e., statistical, internal, construct and external validity, has been used. The chapter especially hones in on construct validity by combining a case-based approach, based on a selection of frequently cited L2-writing process studies, with a comprehensive causal model often used for analyzing writing process studies (in terms of four components, Process – Task – Learner – Output). We suggest seven functional and directional parameters to discuss the construct of the writing process as intended against the construct as studied, and propose a selective and non-exhaustive list of guidelines for statistical and internal validity. Both parameters and guidelines are provided to inform (the design of) future L2 writing process studies.