{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,31]],"date-time":"2026-03-31T14:45:37Z","timestamp":1774968337729,"version":"3.50.1"},"reference-count":32,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2021,9,10]],"date-time":"2021-09-10T00:00:00Z","timestamp":1631232000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"EU EraSME (FP7)","award":["IWT 100404"],"award-info":[{"award-number":["IWT 100404"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>The aging population has resulted in interest in remote monitoring of elderly individuals\u2019 health and well being. This paper describes a simple unsupervised monitoring system that can automatically detect if an elderly individual\u2019s pattern of presence deviates substantially from the recent past. The proposed system uses a small set of low-cost motion sensors and analyzes the produced data to establish an individual\u2019s typical presence pattern. Then, the algorithm uses a distance function to determine whether the individual\u2019s observed presence for each day significantly deviates from their typical pattern. Empirically, the algorithm is validated on both synthetic data and data collected by installing our system in the residences of three older individuals. In the real-world setting, the system detected, respectively, five, four, and one deviating days in the three locations. The deviating days detected by the system could result from a health issue that requires attention. The information from the system can aid caregivers in assessing the subject\u2019s health status and allows for a targeted intervention. Although the system can be refined, we show that otherwise hidden but relevant events (e.g., fall incident and irregular sleep patterns) are detected and reported to the caregiver.<\/jats:p>","DOI":"10.3390\/s21186080","type":"journal-article","created":{"date-parts":[[2021,9,12]],"date-time":"2021-09-12T21:48:01Z","timestamp":1631483281000},"page":"6080","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":7,"title":["Motion Sensor-Based Detection of Outlier Days Supporting Continuous Health Assessment for Single Older Adults"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5480-167X","authenticated-orcid":false,"given":"Marc","family":"Mertens","sequence":"first","affiliation":[{"name":"Mobilab & Care, Thomas More University of Applied Sciences Kempen, Kleinhoefstraat 4, 2440 Geel, Belgium"},{"name":"Department of Computer Science, KU Leuven, 3001 Heverlee, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Glen","family":"Debard","sequence":"additional","affiliation":[{"name":"Mobilab & Care, Thomas More University of Applied Sciences Kempen, Kleinhoefstraat 4, 2440 Geel, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jesse","family":"Davis","sequence":"additional","affiliation":[{"name":"Department of Computer Science, KU Leuven, 3001 Heverlee, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Els","family":"Devriendt","sequence":"additional","affiliation":[{"name":"Department of Public Health and Primary Care, Academic Centre for Nursing and Midwifery, KU Leuven, 3000 Leuven, Belgium"},{"name":"Department of Geriatric Medicine, University Hospitals Leuven, 3000 Leuven, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Koen","family":"Milisen","sequence":"additional","affiliation":[{"name":"Department of Public Health and Primary Care, Academic Centre for Nursing and Midwifery, KU Leuven, 3000 Leuven, Belgium"},{"name":"Department of Geriatric Medicine, University Hospitals Leuven, 3000 Leuven, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jos","family":"Tournoy","sequence":"additional","affiliation":[{"name":"Department of Geriatric Medicine, University Hospitals Leuven, 3000 Leuven, Belgium"},{"name":"Department of Public Health and Primary Care, Gerontology and Geriatrics, University of Leuven, 3000 Leuven, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tom","family":"Croonenborghs","sequence":"additional","affiliation":[{"name":"Department of Computer Science, KU Leuven, 3001 Heverlee, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Bart","family":"Vanrumste","sequence":"additional","affiliation":[{"name":"eMedia ResearchLab and STADIUS, Department of Electrical Engineering (ESAT), KU Leuven, 3001 Heverlee, Belgium"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"104","DOI":"10.1080\/02763890802097144","article-title":"Perceptions and use of gerotechnology: Implications for aging in place","volume":"22","author":"Mahmood","year":"2008","journal-title":"J. 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