“…These efforts have focused on methods that do not rely entirely on measured variables to control for selection, such as instrumental variables, as well as fixed‐effects, difference‐in‐difference, and regression discontinuity analyses (e.g., Duncan et al, ; McCartney et al, ; Miller et al, , for further explanation of these issues). We agree with these ideas and have used these designs in our research (e.g., Dearing, Zachrisson, Mykletun, & Toppelberg, ; Dearing, Zachrisson, & Nærde, ; Zachrisson & Dearing, ). Yet many instances remain in which developmental researchers cannot use these methods, despite their strengths.…”