%0 Journal Article %@ 2561-326X %I JMIR Publications %V 5 %N 5 %P e23461 %T Digital Phenotypes for Understanding Individuals' Compliance With COVID-19 Policies and Personalized Nudges: Longitudinal Observational Study %A Ibrahim,Ahmed %A Zhang,Heng %A Clinch,Sarah %A Poliakoff,Ellen %A Parsia,Bijan %A Harper,Simon %+ Department of Computer Science, The University of Manchester, LF7, Kilburn Building, Kilburn Buidling, Manchester, M13 9PL, United Kingdom, 44 7427630668, heng.zhang@manchester.ac.uk %K behavior %K compliance %K COVID-19 %K digital phenotyping %K nudges %K personalization %K policy %K sensor %K smartphone %D 2021 %7 27.5.2021 %9 Original Paper %J JMIR Form Res %G English %X Background: Governments promote behavioral policies such as social distancing and phased reopening to control the spread of COVID-19. Digital phenotyping helps promote the compliance with these policies through the personalized behavioral knowledge it produces. Objective: This study investigated the value of smartphone-derived digital phenotypes in (1) analyzing individuals’ compliance with COVID-19 policies through behavioral responses and (2) suggesting ways to personalize communication through those policies. Methods: We conducted longitudinal experiments that started before the outbreak of COVID-19 and continued during the pandemic. A total of 16 participants were recruited before the pandemic, and a smartphone sensing app was installed for each of them. We then assessed individual compliance with COVID-19 policies and their impact on habitual behaviors. Results: Our results show a significant change in people’s mobility (P<.001) as a result of COVID-19 regulations, from an average of 10 visited places every week to approximately 2 places a week. We also discussed our results within the context of nudges used by the National Health Service in the United Kingdom to promote COVID-19 regulations. Conclusions: Our findings show that digital phenotyping has substantial value in understanding people’s behavior during a pandemic. Behavioral features extracted from digital phenotypes can facilitate the personalization of and compliance with behavioral policies. A rule-based messaging system can be implemented to deliver nudges on the basis of digital phenotyping. %M 33999832 %R 10.2196/23461 %U https://formative.jmir.org/2021/5/e23461 %U https://doi.org/10.2196/23461 %U http://www.ncbi.nlm.nih.gov/pubmed/33999832