【CHNS】随访时间 整理

As to avoid temporal bias, for example, if an individual participated the first wave in 1997, for cardiovascular outcomes during the 1997–2000 time period, the follow-up period was calculated as the following: [2000–1997 year]/2. Here we summarized the formula as the following: The follow-up period = [(Yn-1-Y1) + (Yn-Yn-1)/2], n ≥ 2. The six rounds of survey were conducted in 1997, 2000, 2004, 2006, 2009 and 2011. In this formula, n indicates the number of times participated in the survey, Yn indicates the survey year of n wave, Yn-1 indicates the survey year of n-1 wave, Y1 indicates the year of the first participation in the survey.

施工中.....
1+1
2+2
3+3