“…For more information, and answers to frequently asked questions about Registered Reports, see https://cos.io/rr/.Registered Reports have been increasingly adopted in journals across the sciences in general, and psychology in particular. Although uptake had initially been slow amongst developmental journals, this has changed considerably in recent years (see Syed et al, 2023, for Registered Reports specifically andSilverstein et al, 2024, for open science and metascience more generally). Nevertheless, there remain many questions about how the format works for complex longitudinal designs and secondary data (van den Akker et al, 2021), both of which are common in developmental research (see also Syed & Donnellan, 2020).…”