# How does hail generates the sample call rate? **URL:** \ **Category:** Hail Query & hailctl\ **Created:** [September 23, 2020, 4:27pm UTC](https://discuss.hail.is/t/how-does-hail-generates-the-sample-call-rate/1701 "2020-09-23T16:27:01Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Maria](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@Maria](https://discuss.hail.is/u/Maria)\ **Post date:** [September 23, 2020, 4:27pm UTC](https://discuss.hail.is/t/how-does-hail-generates-the-sample-call-rate/1701/1 "2020-09-23T16:27:01Z")
Hi there! I was wondering how does hail generate the sample call rate? Are there specific criteria for defining the missing data for the SNPs? Thank you! Maria ---
**Author:** ![danking](https://yyz2.discourse-cdn.com/flex036/user_avatar/discuss.hail.is/danking/32/43_2.png) [@danking](https://discuss.hail.is/u/danking)\ **Post date:** [September 23, 2020, 4:54pm UTC](https://discuss.hail.is/t/how-does-hail-generates-the-sample-call-rate/1701/2 "2020-09-23T16:54:16Z")
Assuming you’re using [`sample_qc`](https://hail.is/docs/0.2/methods/genetics.html#hail.methods.sample_qc), it’s the number of non-missing genotypes (where `hl.is_defined(mt.GT)` is true) divided by the number of rows in the dataset (`mt.count_rows()`). Missingness is defined simply as things that are missing. No special logic is used, nothing about allele frequencies, etc. If you load data from a file, the missing genotypes are exactly the ones explicitly stated as missing in the file. ---
**Author:** ![Maria](https://avatars.discourse-cdn.com/v4/letter/m/34f0e0/32.png) [@Maria](https://discuss.hail.is/u/Maria)\ **Post date:** [September 23, 2020, 4:56pm UTC](https://discuss.hail.is/t/how-does-hail-generates-the-sample-call-rate/1701/3 "2020-09-23T16:56:04Z")
Good to know! Thank you very much for your prompt response.