Dall, P. M.Skelton, D. A.Dontje, Manon L.Coulter, Elaine H.Stewart, SallyCox, Simon R.Shaw, Richard J.Čukić, IvaFitzsimons, C. F.Greig, CarolynGranat, M. H.Der, GeoffDeary, Ian J.Chastin, SFM2018-07-272018-07-272018-04-30Dall, P M and Skelton, DA and Dontje, Manon L. and Coulter, Elaine H and Stewart, Sally and Cox, Simon R. and Shaw, Richard J. and Čukić, Iva and Fitzsimons, CF and Greig, Carolyn and Granat, M H and Der, Geoff and Deary, Ian J. and Chastin, SFM (2018) Characteristics of a Protocol to Collect Objective Physical Activity/Sedentary Behavior Data in a Large Study: Seniors USP (Understanding Sedentary Patterns). Journal for the Measurement of Physical Behaviour, 1(1), pp. 26-31.2575-6613http://dx.doi.org/10.1123/jmpb.2017-0004https://eresearch.qmu.ac.uk/handle/20.500.12289/5353** From Crossref via Jisc Publications Router.The Seniors USP (Understanding Sedentary Patterns) study measured sedentary behavior (activPAL3, 9-day wear) in older adults. The measurement protocol had three key characteristics: enabling 24-hour wear (monitor location, waterproofing), minimizing data loss (reducing monitor failure, staff training, communication), and quality assurance (removal by researcher, confidence about wear). Two monitors were not returned; 91% (n = 700) of returned monitors had seven valid days of data. Sources of data loss included monitor failure (n = 11), exclusion after quality assurance (n = 5), early removal for skin irritation (n = 8), or procedural errors (n = 10). Objective measurement of physical activity and sedentary behavior in large studies requires decisional trade-offs between data quantity (collecting representative data) and utility (derived outcomes that reflect actual behavior).26-31accelerometeradherenceactivPALdata lossmethodologyposturearticlehttp://10.1123/jmpb.2017-0004