Necessary Sample Size Z-score2 StdDev 1-StdDev margin of error2. Can be solved for n yielding n 4 W2 1 B2 where B is the error bound on the estimate ie the estimate is usually given as within B. Dummies helps everyone be more knowledgeable and confident in applying what they know.
Here n 0 is Cochrans sample size recommendation N is the population size and n is the new adjusted sample size.
The z-score is the number of standard deviations a given proportion is away from the mean. Suppose that sample size is 1500 per group for hospital-ization and 2500 for mortality. The standard formula for sample size is. N population size e Margin of error percentage in decimal form z z-score.