title: Multiple Comparison of Age Groups in Bone Mineral Density under Heteroscedasticity.
abstract: Osteoporosis is a silent disease because individuals may not know that they have osteoporosis until their bones become so fragile. Bone mineral density (BMD) test helps to detect osteoporosis and determine the risk fractures. This study covers bone measurement data from total body dual energy X-ray absorptiometry scans for 28,454 persons who participated in the 1996-2006 National Health and Nutrition Examination Survey in USA Dual energy X-ray absorptiometry (DXA) method is known as the primary method for detecting osteoporosis because of its high precision and accuracy. Testing the equality of the means of normal populations when the variances are unknown and unequal is a fundamental problem in clinical trials and biomedical research. In this study we compare age groups based upon BMD in case of unequal variance being present among the groups. First we test equality of variances among the age groups by the Hartley test. And then Scott-Smith test is used to test equality of BMD means for the age groups. Finally, Tukey-Cramer confidence intervals are constructed to detect which groups start to differ from the reference group in which BMD reaches the peak level.
authors.affiliation: Department of Statistics, Faculty of Science, Anadolu University, 26470 Eskisehir, Turkey.
authors.forename: Ahmet
authors.initials: A
authors.lastname: Sezer
authors.affiliation: Department of Physical Medicine and Rehabilitation, Medical Faculty, University of Uludag, 16059 Bursa, Turkey.
authors.forename: Lale
authors.initials: L
authors.lastname: Altan
authors.affiliation: Department of Statistics, Faculty of Science, Anadolu University, 26470 Eskisehir, Turkey.
authors.forename: Özer
authors.initials: Ö
authors.lastname: Özdemir
mesh_terms: D015502:Absorptiometry, Photon; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D015519:Bone Density; D002648:Child; D016208:Databases, Factual; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D010024:Osteoporosis; D012016:Reference Values; D055815:Young Adult