CHART 2.

Sample size calculation to estimate the frequency (prevalence) of sunscreen use in the population, considering different scenarios but keeping the significance level (95%) and the design effect (1.0) constant

Target population	Prevalence (p) of outcome
	Sunscreen use at work p=10%		Sunscreen use in sports p=35%		Sunscreen use at the beach p=50%
	Acceptable Error 2 p.p.		Acceptable Error 5 p.p.		Acceptable Error 2 p.p.	Acceptable Error 5 p.p.	Acceptable Error 2 p.p.	Acceptable Error 5 p.p.
	Sample
Health center users investigated in a single day (population = 100)	90		59		96	78	97	80
All users in the area covered by a health center (population size = 1,000)	464		122		687	260	707	278
All users from the areas covered by all health centers in a city (population size = 10,000)	796		137		1794	338	1937	370
The entire city population (N = 40.000)	847		138		2072	347	2265	381

p.p.= percentage points