# 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.

- Set

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.