# \#observer-variability

**URL:** https://discourse.datamethods.org/tag/observer-variability/60.md

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## [How to assess reliability/validity of a measurement based on differences in measurements?](https://discourse.datamethods.org/t/how-to-assess-reliability-validity-of-a-measurement-based-on-differences-in-measurements/28300)

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**Author:** [@Hanis\_Kadir](https://discourse.datamethods.org/u/Hanis_Kadir)\
**Replies:** 6\
**Last updated:** [August 7, 2025, 5:39am UTC](https://discourse.datamethods.org/t/how-to-assess-reliability-validity-of-a-measurement-based-on-differences-in-measurements/28300 "2025-08-07T05:39:52Z")

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Hi all, I have a methodological question regarding reliability/validity testing for the Modified Weeks Test (MWT) in post-traumatic elbow stiffness assessment. The MWT involves measuring ROM differences before and after…

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## [Cronbach’s alpha](https://discourse.datamethods.org/t/cronbach-s-alpha/5030)

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**Author:** [@Carl](https://discourse.datamethods.org/u/Carl)\
**Replies:** 0\
**Last updated:** [October 26, 2021, 1:51pm UTC](https://discourse.datamethods.org/t/cronbach-s-alpha/5030 "2021-10-26T13:51:29Z")

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In reading peer reviews of manuscripts, as an author and editor, I have noticed an unquestioning value of Cronbach’s alpha as a measure of scientific rigor. High alpha doesn’t mean a good measure and a low alpha doesn’t …

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## [Sample Size for Bland Altman plot](https://discourse.datamethods.org/t/sample-size-for-bland-altman-plot/5014)

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**Author:** [@trumanfrancis](https://discourse.datamethods.org/u/trumanfrancis)\
**Replies:** 1\
**Last updated:** [October 17, 2021, 1:39pm UTC](https://discourse.datamethods.org/t/sample-size-for-bland-altman-plot/5014 "2021-10-17T13:39:02Z")

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Is there a method for determining the minimal sample size for a Blamd Altman plot?

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## [Sample size calculation for intraclass correlation coefficient (ICC)](https://discourse.datamethods.org/t/sample-size-calculation-for-intraclass-correlation-coefficient-icc/3257)

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**Author:** [@agazzi\_giorgio](https://discourse.datamethods.org/u/agazzi_giorgio)\
**Replies:** 0\
**Last updated:** [May 1, 2020, 3:42pm UTC](https://discourse.datamethods.org/t/sample-size-calculation-for-intraclass-correlation-coefficient-icc/3257 "2020-05-01T15:42:50Z")

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I’m a radiology trainee so my statistical background is not so solid. I want to design a study when I’ll be comparing three measurements of a variable in imaging obtained in magnetic resonance and then compute an ICC as …

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## [Statistic Model for Reliability Study](https://discourse.datamethods.org/t/statistic-model-for-reliability-study/3209)

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**Author:** [@Amejiag](https://discourse.datamethods.org/u/Amejiag)\
**Replies:** 2\
**Last updated:** [April 25, 2020, 12:13am UTC](https://discourse.datamethods.org/t/statistic-model-for-reliability-study/3209 "2020-04-25T00:13:39Z")

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Good afternoon, First of all, my name is Alejandro Mejia, i’m a physician currently at residency training in orthopedic and traumatology from Bogotá, Colombia at Pontifical Javerian University I’m developing a reliabil…

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## [What kind of model to use?](https://discourse.datamethods.org/t/what-kind-of-model-to-use/1649)

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**Author:** [@Isabella\_Ghement](https://discourse.datamethods.org/u/Isabella_Ghement)\
**Replies:** 3\
**Last updated:** [May 3, 2019, 10:18am UTC](https://discourse.datamethods.org/t/what-kind-of-model-to-use/1649 "2019-05-03T10:18:38Z")

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I am working on a project where N doctors were asked to prescribe the same medication to the same set of n hypothetical patients. Each doctor could choose a different dose of medication. For the purposes of this questi…

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## [Multiple observations per patient, multiple binary variables, and a binary outcome](https://discourse.datamethods.org/t/multiple-observations-per-patient-multiple-binary-variables-and-a-binary-outcome/231)

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**Author:** [@Martin\_Dahlberg](https://discourse.datamethods.org/u/Martin_Dahlberg)\
**Replies:** 8\
**Last updated:** [August 1, 2018, 6:41am UTC](https://discourse.datamethods.org/t/multiple-observations-per-patient-multiple-binary-variables-and-a-binary-outcome/231 "2018-08-01T06:41:52Z")

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Hi! First of all, great new platform and I’m looking forward to seeing it take off! I have a common situation with Computed Tomography (CT) images in surgical patients, where different observers (radiologists) make dif…