# \#sap

**URL:** https://discourse.datamethods.org/tag/sap/95.md

[Latest](https://discourse.datamethods.org/latest.md) · [Categories](https://discourse.datamethods.org/categories.md) · [Tags](https://discourse.datamethods.org/tags.md)

---

## [Statistical Analysis Plans](https://discourse.datamethods.org/t/statistical-analysis-plans/28514)

<div class="topic-metadata">

**Author:** [@f2harrell](https://discourse.datamethods.org/u/f2harrell)\
**Replies:** 2\
**Last updated:** [November 2, 2025, 10:10pm UTC](https://discourse.datamethods.org/t/statistical-analysis-plans/28514 "2025-11-02T22:10:40Z")

</div>

The purpose of this topic is to provide resources for writing prospective statistical analysis plans (SAPs) and to provide a place to collect suggested resources from a wider community. Primary Resources A template for…

---

## [Random effects analysis in clinical trials](https://discourse.datamethods.org/t/random-effects-analysis-in-clinical-trials/28517)

<div class="topic-metadata">

**Author:** [@alvespedros](https://discourse.datamethods.org/u/alvespedros)\
**Replies:** 2\
**Last updated:** [November 4, 2025, 11:36am UTC](https://discourse.datamethods.org/t/random-effects-analysis-in-clinical-trials/28517 "2025-11-04T11:36:54Z")

</div>

Hello, I’m working on a SAP for a clinical trial with three levels of clustering: physicians, hospitals, and cities. My outcome is binary, and I’m particularly interested in the conditional interpretation of the odds ra…

---

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

<div class="topic-metadata">

**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")

</div>

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…

---

## [Change of study design of an ongoing clinical trial](https://discourse.datamethods.org/t/change-of-study-design-of-an-ongoing-clinical-trial/6857)

<div class="topic-metadata">

**Author:** [@choileena](https://discourse.datamethods.org/u/choileena)\
**Replies:** 4\
**Last updated:** [June 9, 2023, 1:12pm UTC](https://discourse.datamethods.org/t/change-of-study-design-of-an-ongoing-clinical-trial/6857 "2023-06-09T13:12:56Z")

</div>

I have a general question about a statistical analysis plan (SAP) and the change of study design of an ongoing trial. Suppose you joined a study team while a trial is ongoing, which was designed with a traditional non-s…

---

## [Sample size estimation for observational studies using Bayesian methods](https://discourse.datamethods.org/t/sample-size-estimation-for-observational-studies-using-bayesian-methods/6496)

<div class="topic-metadata">

**Author:** [@Miiro\_Emmanuel](https://discourse.datamethods.org/u/Miiro_Emmanuel)\
**Replies:** 2\
**Last updated:** [March 15, 2023, 11:17am UTC](https://discourse.datamethods.org/t/sample-size-estimation-for-observational-studies-using-bayesian-methods/6496 "2023-03-15T11:17:57Z")

</div>

I am designing a clinical observational study. My statistical analysis plan is to use a Bayesian modelling framework. However, I have not come across practical tutorials on sample size calculations using Bayesian framewo…

---

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

<div class="topic-metadata">

**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")

</div>

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…

---

## [Best practices for recording race/ethnicity](https://discourse.datamethods.org/t/best-practices-for-recording-race-ethnicity/3431)

<div class="topic-metadata">

**Author:** [@LRSamuels](https://discourse.datamethods.org/u/LRSamuels)\
**Replies:** 14\
**Last updated:** [June 23, 2020, 2:49pm UTC](https://discourse.datamethods.org/t/best-practices-for-recording-race-ethnicity/3431 "2020-06-23T14:49:49Z")

</div>

What are some examples of race/ethnicity questionnaire items that honor people’s right to identify and describe themselves while also complying with US OMB guidelines and leading to manageable data? One example I have s…

---

## [Open label RCT: Placebo or Real effect?](https://discourse.datamethods.org/t/open-label-rct-placebo-or-real-effect/2804)

<div class="topic-metadata">

**Author:** [@Raj](https://discourse.datamethods.org/u/Raj)\
**Replies:** 5\
**Last updated:** [February 5, 2020, 4:51pm UTC](https://discourse.datamethods.org/t/open-label-rct-placebo-or-real-effect/2804 "2020-02-05T16:51:39Z")

</div>

Lancet recently published a great RCT in oseltamivir, using a Bayesian analysis: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(19)32982-4/fulltext Of interest, this study was open-label. The goal was …

---

## [Power and Sample Size Calculations in Pilot Studies](https://discourse.datamethods.org/t/power-and-sample-size-calculations-in-pilot-studies/437)

<div class="topic-metadata">

**Author:** [@ADAlthousePhD](https://discourse.datamethods.org/u/ADAlthousePhD)\
**Replies:** 13\
**Last updated:** [December 3, 2019, 4:19pm UTC](https://discourse.datamethods.org/t/power-and-sample-size-calculations-in-pilot-studies/437 "2019-12-03T16:19:37Z")

</div>

This happens from time to time: I work with someone that is putting together an application for a pilot study, usually with a funding mechanism / budget that will only support enrollment of a few dozen subjects that is c…

---

## [How to pre-specify the statistical analysis strategy in RCTs?](https://discourse.datamethods.org/t/how-to-pre-specify-the-statistical-analysis-strategy-in-rcts/1912)

<div class="topic-metadata">

**Author:** [@BrennanKahan](https://discourse.datamethods.org/u/BrennanKahan)\
**Replies:** 5\
**Last updated:** [July 26, 2019, 10:01pm UTC](https://discourse.datamethods.org/t/how-to-pre-specify-the-statistical-analysis-strategy-in-rcts/1912 "2019-07-26T22:01:08Z")

</div>

Hi everyone, We would like to get your feedback on a preprint we’ve written on how the statistical analysis approach in a randomised trial should be pre-specified: https://arxiv.org/ftp/arxiv/papers/1907/1907.04078.pdf …

---

## [Protocol deviation and its impact on stat analysis](https://discourse.datamethods.org/t/protocol-deviation-and-its-impact-on-stat-analysis/832)

<div class="topic-metadata">

**Author:** [@pakeezahs](https://discourse.datamethods.org/u/pakeezahs)\
**Replies:** 8\
**Last updated:** [October 21, 2018, 12:13pm UTC](https://discourse.datamethods.org/t/protocol-deviation-and-its-impact-on-stat-analysis/832 "2018-10-21T12:13:55Z")

</div>

Hi, First time poster here and grad student in health research methods. Quick question on methodology and how that impacts the statistical anlaysis (cox model): If a trial with 3 arms makes a change in one of the arms …