# \#ancova

**URL:** https://discourse.datamethods.org/tag/ancova/113.md

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## [Sample Size Calculation for a 2x2 Factorial RCT](https://discourse.datamethods.org/t/sample-size-calculation-for-a-2x2-factorial-rct/28345)

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**Author:** [@mksp](https://discourse.datamethods.org/u/mksp)\
**Replies:** 6\
**Last updated:** [September 3, 2025, 7:25am UTC](https://discourse.datamethods.org/t/sample-size-calculation-for-a-2x2-factorial-rct/28345 "2025-09-03T07:25:06Z")

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Experts! I would appreciate a sanity check on my sample size calculation for an upcoming study. Study Design: We’re using a 2x2 factorial design to evaluate two interventions for reducing the hemodynamic stress respons…

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## [Guidelines for Covariate Adjustment in RCTs](https://discourse.datamethods.org/t/guidelines-for-covariate-adjustment-in-rcts/2814)

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**Author:** [@pau13rown](https://discourse.datamethods.org/u/pau13rown)\
**Replies:** 62\
**Last updated:** [October 9, 2022, 6:24pm UTC](https://discourse.datamethods.org/t/guidelines-for-covariate-adjustment-in-rcts/2814 "2022-10-09T18:24:24Z")

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i’m susceptible to concise recommendations, thus i like this paper and tempted to share it. “Covariate adjustment for randomized controlled trials revisited” Although it is very difficult to make general recommendation…

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## [Use of adjusted response variables vs. adjusting them for covariates](https://discourse.datamethods.org/t/use-of-adjusted-response-variables-vs-adjusting-them-for-covariates/4354)

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**Author:** [@doctorShawniqua](https://discourse.datamethods.org/u/doctorShawniqua)\
**Replies:** 3\
**Last updated:** [May 6, 2021, 12:50pm UTC](https://discourse.datamethods.org/t/use-of-adjusted-response-variables-vs-adjusting-them-for-covariates/4354 "2021-05-06T12:50:13Z")

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I’ve been told that it is unwise to build a model in which the outcome variable is adjusted (e.g. for age) while the independent variable is not. I imagine this would be even more of a problem when the model itself adjus…

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## [ANCOVA with randomized and nonrandomized groups](https://discourse.datamethods.org/t/ancova-with-randomized-and-nonrandomized-groups/3797)

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**Author:** [@arcaldwell49](https://discourse.datamethods.org/u/arcaldwell49)\
**Replies:** 4\
**Last updated:** [September 30, 2020, 6:27pm UTC](https://discourse.datamethods.org/t/ancova-with-randomized-and-nonrandomized-groups/3797 "2020-09-30T18:27:37Z")

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I was recently discussing a study and I was presented with an interesting scenario. In this hypothetical, there is a crossover RCT where all participants have pre-test values obtained on a physiological outcome variable…

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## [MERINO trial - adjusting for infection source](https://discourse.datamethods.org/t/merino-trial-adjusting-for-infection-source/3615)

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**Author:** [@Gus\_Hamilton](https://discourse.datamethods.org/u/Gus_Hamilton)\
**Replies:** 3\
**Last updated:** [August 3, 2020, 6:13pm UTC](https://discourse.datamethods.org/t/merino-trial-adjusting-for-infection-source/3615 "2020-08-03T18:13:47Z")

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Hi all You have helped me before and I come again :smiley: ! This is an interesting trial, for many reasons. It compares two antibotics, both very broad spectrum, for a set of resistant bugs (ESBL E.coli + Klebsiella…

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## [Sample size considerations for interaction covariate adjustment](https://discourse.datamethods.org/t/sample-size-considerations-for-interaction-covariate-adjustment/1618)

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**Author:** [@wberry](https://discourse.datamethods.org/u/wberry)\
**Replies:** 11\
**Last updated:** [May 3, 2019, 2:23pm UTC](https://discourse.datamethods.org/t/sample-size-considerations-for-interaction-covariate-adjustment/1618 "2019-05-03T14:23:20Z")

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I am working with a clinician who is interested in running a relatively simple RCT, comparing therapeutic efficacy of a treatments pain reduction compared to a placebo during a painful gynecologic procedure (endometrial …

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## [Inequality of Variances in an RCT](https://discourse.datamethods.org/t/inequality-of-variances-in-an-rct/1124)

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**Author:** [@venkmurthy](https://discourse.datamethods.org/u/venkmurthy)\
**Replies:** 12\
**Last updated:** [December 27, 2018, 12:01am UTC](https://discourse.datamethods.org/t/inequality-of-variances-in-an-rct/1124 "2018-12-27T00:01:45Z")

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Prof. Harrell has wisely suggested moving another twitter discussion on statistics here. The original discussion is found here (https://twitter.com/RogueRad/status/1074730161617231873) There are several issues: (1) The…