# Sample Size for a PGS Target Sample

**URL:** <https://isgw-forum.colorado.edu/t/sample-size-for-a-pgs-target-sample/823>\
**Category:** Day 5\
**Created:** [June 8, 2026, 5:11pm UTC](https://isgw-forum.colorado.edu/t/sample-size-for-a-pgs-target-sample/823 "2026-06-08T17:11:07Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![anonymous](https://isgw-forum.colorado.edu/letter_avatar_proxy/v4/letter/a/8491ac/32.png) [@anonymous](https://isgw-forum.colorado.edu/u/anonymous)\
**Post date:** [June 8, 2026, 5:11pm UTC](https://isgw-forum.colorado.edu/t/sample-size-for-a-pgs-target-sample/823/1 "2026-06-08T17:11:07Z")

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what is generally considered a good sample size for a PGS target sample population?

> Replying to “what is generally considered a good sample size fo…”:

depends on the heritability of the trait and sample size of the GWAS

> Replying to “what is generally considered a good sample size fo…”:

As big as possible - you can check power using a standard regression power calculator

> Replying to “what is generally considered a good sample size fo…”:

Can rare variants included in PRS analysis increase the prediction accuracy of the trait?

> Replying to “what is generally considered a good sample size fo…”:

technically yes - in practice it depends on how rare they are

> Replying to “what is generally considered a good sample size fo…”:

it should, but methods require LD reference data, which should then also include the rare variants

> Replying to “what is generally considered a good sample size fo…”:

also keep in mind that rare variants, by virtue of being rare, are probably not going to explain much variance in the sample