Some Considerations Affectiong the Design of Follow-Up Studies | ||
The Egyptian Statistical Journal | ||
Article 5, Volume 19, Issue 2, December 1975, Pages 121-142 PDF (13.53 M) | ||
Document Type: Original Article | ||
DOI: 10.21608/esju.1975.315759 | ||
Authors | ||
Mindel C. Sheps* 1; Ahmed Fathy Mahmoud Mustafa2 | ||
1School of Public Health, University of North Carolina, USA. | ||
2Institute of Statistical Studies and Research, Cairo University, Egypt. | ||
Abstract | ||
When a reasonable basis exists for postulating the distribution of risks (or of survival times) in a population, it may also provide a basis for choosing a desirable combination of sample size (n) and duration of follow-up (t). In studies of conception risk, if a Beta distribution of risks is assumed, the asymptotic precision and bias of maximum likelihood estimators of the parameters are improved by a moderate prolongation of t. Not surprisingly, the desirable value of t increases as the mean risk decreases, i.e. as the probability of "survival" beyond a fixed t increases. | ||
Keywords | ||
Design of Follow; Up Studies; Survival Times; Maximum Likelihood Estimators | ||
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