It might be Survival that determines Shopping !
Giridhara R Babu, Assistant Professor,
October 28, 2011
Sir, I read with interest the article by Yu-Hung Chang et al.(1) Authors have articulated some limitations in their paper. However, the findings are derived from purpose of the Elderly Nutrition and Health Survey in Taiwan (1999-2000), done to assess the diet, nutrition and health of persons aged 65 and above in Taiwan. One of the common and often forgotten limitation of such surveys is Survivor Bias.(2) People who go to shopping might be those who are healthy and survived minor illness. Hence, Survival is a determinant of whether people remain active and whether they can go to shopping. Also, people who are debilitated, disabled and who have severe illness might not be able to go to shopping at all. It will be interesting to know whether authors have considered this limitation and if yes, why have they not chosen to discuss regarding this in their paper. References:- 1. Chang Y-H, Chen RC-Y, Wahlqvist ML, et al. J Epidemiol Community Health (2011). doi:10.1136/jech.2010.12669 2. Giridhara R Babu.Do you see an elephant or just its trunk? The need of learning Modern Epidemiologic Methods: An introduction. The Internet Journal of Epidemiology. 2011 Volume 10 Number 1 (Under Print)
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