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Table 3 Estimated Intra-class correlations (ICC) 1 and calculated sample sizes 2 for variables measured daily over the entire study

From: Procedures for assessing psychological predictors of injuries in circus artists: a pilot prospective study

Variable Estimated ICC1 Estimated sample size2
Feeling today 0.35 950
Hours slept 0.34 941
Ill past 24 hours 0.16 828
Whole body soreness 0.41 1011
Art soreness 0.46 1075
Leg soreness 0.40 1000
Confidence 0.58 1301
Anxiety 0.56 1254
Fatigue 0.32 924
  1. 1ICC was calculated as within subject variance/total variance within a linear regression random effects model.
  2. 2Sample sizes calculated using matched case–control design and the following parameter values: alpha = 0.05, power = 0.8, 10:1 ratio of controls to cases, risk of exposure (categorized dichotomously) in controls at 0.3, and an increased risk of exposure in cases at 20%.