“…Power was estimated by a program developed by Ackerman and Kenny (2016), which was designed to determine the sample size needed to detect small and moderate effects for APIM. We used this program similarly to previous longitudinal studies in couples (van Scheppingen, Chopik, Bleidorn, & Denissen, 2018;Weidmann, Sch€ onbrodt, Ledermann, & Grob, 2017), as no other existing tool was specifically designed for estimating the statistical power in dyadic growth models, to the best of our knowledge. Following recommendations by Ackerman and Kenny (2016), and based on previous research (Mizrahi, Kanat-Maymon, & Birnbaum, 2018), we expected actor effects to be medium in size (i.e., b~.25), and partner effects to be smaller (i.e., b~.15).…”