With the data obtained from the complete texts of prospective studies, aleatory and controled and whose populations and designs were homogeneous, 2X2 tables were constructed on which were calculated the value of p with the Mantel-Haenszel correction; and for the tables whose values were less than 5, the value of p with the Fisher test, employing the Epi-Info software 20.
Con los datos obtenidos a partir de los textos completos de estudios prospectivos, aleatorios y controlados, cuyas poblaciones y diseños fueran homogéneos, se elaboraron tablas de 2x2 con las cuales se calculó el valor de p con correción Mantel-Haenszel, y para tablas con valores menores de 5 el valor p con el test de exactitud de Fisher, utilizando el software Epi-Info 20.