A pilot study was first performed with 50 food handlers being 10
from each business, to calculate the necessary sample size and to test comprehension of the questionnaires. Minor adjustments were
necessary to improve understanding of the questionnaires.The
sample size was calculated considering at least one point of dif-ference on knowledge score and a 95% of global confidence interval.
Based on the data, 42 randomly selected food handlers for each group (trained and untrained) were necessary to have a sample
with 0.80 of sample power