Formula For Required Sample Size. Where n i is the sample size required in each group i12 Z is the value from the standard normal distribution reflecting the confidence level that will be used eg Z 196 for 95 and E is the desired margin of error. Nfrac 1000 11000005005 286 n 110000050051000 286 The survey therefore needs to include 286 employees.
In order to calculate the sample size yourself you will need to use this equation. Where n 0 is the sample size z is the abscissa of the. This equation is for an unknown population size or a very large population size.
Plug in your Z-score standard of deviation and confidence interval into the sample size calculator or use this sample size formula to work it out yourself.
The second method is to use the formula for the sample size for the mean. Dummies has always stood for taking on complex concepts and making them easy to understand. The formulation depends on the t distribution where the minimum sample size is given by begineqnarray N t_1-alpha2 t_1-beta2 left fracsdelta right2 rightarrow two-sided test N t_1-alpha t_1-beta2 left fracsdelta right2 rightarrow one-sided test endeqnarray. Thus 186 sample size arrived at should be corrected adjusted for finite population.
