# \#variability

**URL:** https://discourse.datamethods.org/tag/variability/128.md

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## [Accounting for period effect in crossover studies with washout](https://discourse.datamethods.org/t/accounting-for-period-effect-in-crossover-studies-with-washout/28234)

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**Author:** [@Matthew\_Rich](https://discourse.datamethods.org/u/Matthew_Rich)\
**Replies:** 0\
**Last updated:** [July 2, 2025, 2:21pm UTC](https://discourse.datamethods.org/t/accounting-for-period-effect-in-crossover-studies-with-washout/28234 "2025-07-02T14:21:44Z")

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What is the general approach for handling data where a period effect appears to be present. So I have a bunch of studies some of which are cross over designs, where the patient is exposed to a drug more than once and EDA…

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## [Estimating variance with heteroscedastic regression models](https://discourse.datamethods.org/t/estimating-variance-with-heteroscedastic-regression-models/4288)

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**Author:** [@RMazzolari001](https://discourse.datamethods.org/u/RMazzolari001)\
**Replies:** 2\
**Last updated:** [April 22, 2021, 2:13am UTC](https://discourse.datamethods.org/t/estimating-variance-with-heteroscedastic-regression-models/4288 "2021-04-22T02:13:39Z")

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I am concerned that the variability in oxygen consumption in response to exercise might depend on the individual’s fitness: less ‘fit’ individuals might show a larger variability than more ‘fit’ individuals. I only have…

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## [Considerations about coefficient of variation in clinical practice](https://discourse.datamethods.org/t/considerations-about-coefficient-of-variation-in-clinical-practice/3364)

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**Author:** [@agazzi\_giorgio](https://discourse.datamethods.org/u/agazzi_giorgio)\
**Replies:** 1\
**Last updated:** [May 20, 2020, 2:35am UTC](https://discourse.datamethods.org/t/considerations-about-coefficient-of-variation-in-clinical-practice/3364 "2020-05-20T02:35:18Z")

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Let assume we have a set of measurements made with a novel instrument and we want to identify some that could be clinically meaningful between all the one we wave. This is a problem that I’m encountering often since the …

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## [Comparing pre/post variance by cluster](https://discourse.datamethods.org/t/comparing-pre-post-variance-by-cluster/2693)

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**Author:** [@mcloshe](https://discourse.datamethods.org/u/mcloshe)\
**Replies:** 4\
**Last updated:** [November 16, 2019, 8:12pm UTC](https://discourse.datamethods.org/t/comparing-pre-post-variance-by-cluster/2693 "2019-11-16T20:12:12Z")

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I am wondering if anyone can suggest a way forward with an analysis I am perplexed with. CTAS is a 5-point ordinal (some could argue categorical) scale used in many emergency departments for establishing the priority by…

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## [How much patient variability is best for a clinical trial?](https://discourse.datamethods.org/t/how-much-patient-variability-is-best-for-a-clinical-trial/2179)

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**Author:** [@f2harrell](https://discourse.datamethods.org/u/f2harrell)\
**Replies:** 5\
**Last updated:** [September 22, 2019, 3:07pm UTC](https://discourse.datamethods.org/t/how-much-patient-variability-is-best-for-a-clinical-trial/2179 "2019-09-22T15:07:45Z")

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We know that with respect to a continuous outcome variable Y, the variation over patients that one seeks in, say, a two-treatment parallel group randomized trial is a minimum. That way the standard deviation of Y is sma…