Table 3

Sample size table for generic continuous outcome.

ICCPowerCohen's d One lookLong-term follow-up with multiple looks
1 year5 years10 years
nnnn
0.050.80.3131187167151
0.250.80.3104147132119
0.50.80.369988880
0.050.90.3181246220198
0.250.90.3143194173157
0.50.90.396130116105
0.050.80.547686055
0.250.80.538534843
0.50.80.525363229
0.050.90.566897972
0.250.90.552706357
0.50.90.535474238
  • Rows correspond to various levels of power, intraclass correlation coefficient (ICC) and effect size (measured by Cohen’s d). Columns provide sample size for one look or assessment and continual monitoring with multiple looks or assessments at 1, 5 and 10 years. The type I error for ‘one look’ is controlled at 5% and for ‘multiple looks’ is jointly controlled at 5% using Bonferroni’s method.