In Survey sampling we need to calculate the desired sample size for different kind of scenarios. Hence it will be great help if there is a good resource for the same.
One of the commonly used formulas for calculating the ideal sample size from a given universe is the Krejcie and Morgan formula (1970). In fact, one does not even have to calculate it as there is a pre-calculated table that allows the researcher to identify the ideal sample size simply by looking at the size of the univerise.