Sample size calculation:
Sample sizes were estimated individually for each item of quality of
life (symptoms, emotions, activity limitation)for children and
(emotions, activity limitations) for caregivers based on the study
published by Nair, et al. Maximum sample size was found for the symptom
item of quality of life of patients (4.512 ± 1.689)12.
The required sample size with an estimation of error of 5% and 95%
confidence level was calculated to be 216. Thus the sample size of the
study is 216 children and equal number of caregivers (216).
Following formula was used for calculating the sample size:
Sample Size (n) ≥ [Z1-α/2 σ/d] 2
Where Z1-α/2 = 1.96 (For 95% confidence level)
σ is the standard deviation of the QOL score
d is the estimation error (5% of the expected average (4.512))
An inflation of 15% was added to compensate for non-response, so the
total sample size was 216 + 30 = 246