By default, this preference is set to "Yes". This means that prices for out-of-stock products (if still visible on the webpage) will be displayed in the reports and included in the Price Position calculation.
If "No" is selected, prices for out-of-stock products will not be displayed in the reports, even if the price information is available on the product page. They will also be excluded from the Price Position calculation.
Changes to this setting may take some time to apply.