Steps for sample size (Cochran's formulas):
I. Cochran's sample size formula for categorical data for an alpha level a priori at .05 (error of 5%) = n0=(t)2*(p)(q)/(d)2=384
Where: n0 is the sample size, t is the value for the selected alpha level, e.g. 1.96 for (0.25 in each tail) a 95 percent confidence level. p is the estimated proportion of an attribute that is present in the population. q is 1-p. (p)(q) are the estimate of variance. d is the acceptable margin of error for proportion being estimated, so the confidence interval, in decimals.
II. Cochran’s correction formula, when pop. <50.000 is: n1 = 384/(1+384/528)= 222
Where: population size =528 Where n0 = required return sample size according to Cochran’s formula= 384 Where n1 = required return sample size because sample > 5% of population
Reference: Cochran, W. G. (1977). Sampling techniques (3rd ed.). New York: John Wiley & Sons.
I would like to learn sample size calculation for complex baseline study and evaluation
Thanks
Yeshewamebrat