# Sample size determination for observational studies

**URL:** <https://discourse.datamethods.org/t/sample-size-determination-for-observational-studies/4973>\
**Category:** design\
**Tags:** observational, sample-size\
**Created:** [October 4, 2021, 8:45am UTC](https://discourse.datamethods.org/t/sample-size-determination-for-observational-studies/4973 "2021-10-04T08:45:59Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![MSchwartz](https://discourse.datamethods.org/user_avatar/discourse.datamethods.org/mschwartz/32/2579_2.png) [@MSchwartz](https://discourse.datamethods.org/u/MSchwartz)\
**Post date:** [October 4, 2021, 1:40pm UTC](https://discourse.datamethods.org/t/sample-size-determination-for-observational-studies/4973/3 "2021-10-04T13:40:28Z")

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Hi,

You might want to review the following two threads:

> [@Sample size estimation](https://discourse.datamethods.org/t/sample-size-estimation/3910):
>
> Hello, I want to design a registry study. However, the sample size will need multiple country registries as any one country will not have enough sample size. How do I determine the sample size for each country and when to stop so that the meta-analysis later will have enough power? If only study level data can be used for the meta-analysis, will that cause a problem? How do we convince the agency? Thank you so much! Kind regards, Huifang

and:

> [@Power analysis in observational studies](https://discourse.datamethods.org/t/power-analysis-in-observational-studies/4095):
>
> Does anyone have a good reference about power analysis in observational studies, mostly retrospective ones? I have read conflicting opinions on this topic.

as they cover this topic and related issues.

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