Segments Used for Average

This determines how many latest segments are used to calculate your average difference to Gold in each split.
For example, if it is set to 10, then the 10 most recent completions of a split are used to find the average difference.

Outlier Threshold (%)

This determines how far off Gold a segment time can be before being excluded from your average.
For example, if it is set to 50%, then with a Gold of 2:00, all times above 3:00 will be excluded from your average.
This is because 3:00 is 50% above 2:00.

This also helps remove issues with skipped splits, as Livesplit merges the times into one and damages the average.