摘要：One of the most common challenges in biomedical and psychosocial research is missing data, which occurs when respondents refuse to provide answers to sensitive questions and when study subjects are lost to follow-up during the repeated assessments of longitudinal trials. This paper is the first in a 3-part series focusing on this important topic; it describes different types of missing data and their differential effects on model estimates, focusing on study design strategies that can be used to prevent or minimize missing data and, thus, maintain the scientific integrity of the research. The second paper in the series will discuss implementation strategies

摘要：*** Power and sample size estimation constitutes an important component of designing and planning modern scientific *** provides information for assessing the feasibility of a study to detect treatment effects and for estimating the resources needed to conduct the *** tutorial discusses the basic concepts of power analysis and the major differences between hypothesis testing and power *** also