# LDSC for rG -\> Neff or N

**URL:** https://isgw-forum.colorado.edu/t/ldsc-for-rg-neff-or-n/724
**Category:** Downstream analysis with genomic data
**Created:** [March 20, 2025, 2:42pm UTC](https://isgw-forum.colorado.edu/t/ldsc-for-rg-neff-or-n/724 "2025-03-20T14:42:12Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![JamesHart](https://isgw-forum.colorado.edu/letter_avatar_proxy/v4/letter/j/f07891/32.png) [@JamesHart](https://isgw-forum.colorado.edu/u/JamesHart)
#### Post date: [March 20, 2025, 2:42pm UTC](https://isgw-forum.colorado.edu/t/ldsc-for-rg-neff-or-n/724/1 "2025-03-20T14:42:12Z")

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Hi everyone!  
Does it matter if you use N effective or N total, when running LDSC for cross trait rG? I’m aware it will impact heritability estimates but not sure if only worried about rG.

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### Author: ![Ralph\_Porneso](https://isgw-forum.colorado.edu/user_avatar/isgw-forum.colorado.edu/ralph_porneso/32/559_2.png) [@Ralph\_Porneso](https://isgw-forum.colorado.edu/u/Ralph_Porneso)
#### Post date: [April 21, 2026, 12:29pm UTC](https://isgw-forum.colorado.edu/t/ldsc-for-rg-neff-or-n/724/2 "2026-04-21T12:29:06Z")

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You need h2\_1 and h2\_2 to move from covG to rG and you also need N (or Neff) to calculate covG. The original 2015 paper from Bulik-Sullivan et al ( [An atlas of genetic correlations across human diseases and traits | Nature Genetics](https://www.nature.com/articles/ng.3406) ) doesn’t distinguish between N and Neff. I assume Neff should be used, but I don’t know this for sure.

Do the sumstats of the traits you are interested in provide both N and Neff? Would love to hear from the faculty myself regarding your question.