The sample size estimation was performed using Power Calculator http://www.dssresearch.com/KnowledgeCenter/toolkitcalculators/samplesizecalculators.aspx.
La estimación del tamaño de la muestra se hizo con el Power Calculator http://www.dssresearch.com/KnowledgeCenter/toolkitcalculators/samplesizecalculators.aspx.
A estimativa do tamanho da amostra foi feita com o uso do Power Calculator http://www.dssresearch.com/KnowledgeCenter/toolkitcalculators/samplesizecalculators.aspx.