WHS Logic and Data Quality

This page summarizes the calculation logic used by the app. For terminology, see the HCPI Glossary.

Score Differential

SD = (113 / Slope) x (GBE - Course Rating - PCC)

Inputs:

• GBE
• Course Rating
• Slope Rating
• PCC

HCPI overview

• Based on the lowest 8 of the latest 20 Score Differentials.
• With fewer than 20 rounds, HCPI uses WHS adjustment steps for Handicap Index.
• Protective mechanics such as Soft Cap and Hard Cap may apply.

9-hole rounds

For 9-hole results, the app uses a dedicated SD logic including half PCC and an additional term based on HCPI Tee Off.

Why can the value differ slightly from the federation’s official scoring record?

The adjustment for the unplayed second nine is calculated using a continuous formula (see above), not a stepped table. The result is rounded to one decimal place only after the base differential and the adjustment have been added together - exactly as required by the official WHS rule. If the unrounded value is close to a rounding threshold (e.g. 15.745 instead of 15.700), an HCPI value that differs only slightly - and that the federation may hold internally with somewhat more precision - can cause the rounded result to differ by 0.1 from the official scoring record (e.g. 15.7 instead of 15.8). This only affects 9-hole rounds and is not a calculation error, but an inherent rounding edge case in the WHS formula - it does not occur for 18-hole rounds, since no additional adjustment is calculated there.

Data maintenance recommendations

• Keep club and course names consistent.
• Maintain tee boxes exactly as played.
• Set PCC only when officially confirmed; otherwise keep 0.
• Create a backup before structural changes.