Methodology
Design: Randomized, true experimental, pretest-posttest, control group, and single blind (research assistant)
Setting: The 60-bed pediatric surgical ward in Thailand
Sample size: Power Analysis Parameters (Cohen,1988):
a) Probability of a type one error of .05
b) Power of .80
c) Medium effect size of .25 (Bosserrt, 1994; Hart & Bossert,1994; Lizasoain & Polaino, 1995)
Expected Sample Size: (N=128) n = 64 / gr. for F test on two means with equal sample size in the ANCOVA
Final sample size: N= 104 (Ex = 53, Con = 51)