9 Interesting Example: Breast Cancer Incidence: ~1 % (0.8 %)(i.e. a positive result should be detected for approximately in every 100 women tested)Sensitivity: ~90 % (87 %)(the mammogram is sensitive enough that approximately in every 100 breast cancer patients will receive a positive result)Specificity: ~90 % (93 %)(the mammogram is specific enough that approximately in every 100 healthy patients will receive a negative result).Data from Kerlikowske et al. (1996)
10 Quick TestWhat is the probability that a patient receiving a positive result actually has breast cancer?
21 Measurement ErrorsUltimately, reliability is dependent on the degree of measurement error in a given studyThe overall error in any measurement is comprised of both systematic and random errorWe will address measurement error further next week…
22 Literature Search Assignment The handout lists 8 questions which can be answered through retrieving the corresponding source articlesAnswer as many as possible and hand them in at next week’s lectureDoes not contribute to final assessment but will be markedDO NOT contact author or order articles.
23 Selected ReadingAtkinson, G. and A. M. Nevill. Statistical methods for assessing measurement error (Reliability) in variables relevant to sports medicine. Sports Medicine. 26: , 1998.Holmes, T. H. Ten categories of statistical errors: a guide for research in endocrinology and metabolism. American Journal of Physiology. 286: EThomas J. R. & Nelson J. K. (2001) Research Methods in Physical Activity, 4th edition. Champaign, Illinois: Human Kinetics