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Table 1 Phases of the Whitehall II cohort study ( http://www.ucl.ac.uk/whitehallII/study-phases )

From: Predictors of two forms of attrition in a longitudinal health study involving ageing participants: An analysis based on the Whitehall II study

Phase Dates Type Number of participants Response Rate
1 1985-1988 Screening / questionnaire 10,308 73% of those invited
2 1989-1990 Questionnaire 8,132 79% of Phase 1 responders
3 1991-1994 Screening / questionnaire 8,815 86% of Phase 1 responders
4 1995-1996 Questionnaire 8,628 84% of Phase 1 responders
5 1997-1999 Screening / questionnaire 7,870 76% of Phase 1 responders
6 2001 Questionnaire 7,355 71% of Phase 1 responders
7 2002-2004 Screening / questionnaire 6,967 68% of Phase 1 responders
8 2006 Questionnaire 7,173 70% of Phase 1 responders
9 2007-2009 Screening / questionnaire 6,761 66% of Phase 1 responders