Finite Population Correction
The finite population correction is used when the sample size is a large fraction (approximately 5% or more) of the total population. You can apply a finite population correction in Q as a design effect on a table.
The formula for the finite population correction is , where is the total population and is the sample size. However, when calculating this correction for use as a design effect in Q, you should not use the square root.
To apply this correction to a table you should:
- Calculate the correction outside of Q. Remember to use (i.e., without the square root).
- Select the table and go to Edit > Table Options > Statistical Assumptions.
- Set Proportions to z-test and uncheck Bessel's correction.
- Set Weights and significance to Un-weighted sample size in tests.
- Put the finite population correction that you calculated previously in the Extra deff field.
Note that this procedure applies to the whole table, so if you have a table with multiple sub-populations, you should filter the table to only show the sub-population of interest.