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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%.
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BMC Medical Research Methodology

ISSN: 1471-2288

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