Research Methods · N-of-1 designs

An ABAB design with a data table and honest limitations

Research Methods › N-of-1 designs effect size confounding worked example

system_suitabilityTL3Analytical chemist29 Jul 2025#1

An ABAB design with a data table and honest limitations Writing it up because I had to work it out twice and would rather nobody else did.

Session topic: SURPASS-4 (Lancet, 2021). Please read it before posting; the discussion is much better when everyone has.

The question I would like us to start with is what the trial set out to estimate, rather than what it found. Once that is on the table we can talk about whether the design could have answered it, and only then about the numbers.

Specific things I would like covered: the population and how far it generalises, how discontinuation was handled, whether the comparator was a fair one, and what the absolute rather than relative effect looks like.

I will summarise at the end and the summary will feed the relevant digest page.

12 likes 12mo

d.szymanskiTL3Wiki editor27 Nov 2025#2

Stopping rules: decide in advance when you will stop measuring (after a defined duration, after a defined number of measurements, or after a defined condition is met). Not deciding in advance means stopping when the result satisfies you, which is bias.

1 like 8mo

e.ferreiraTL3Regular23 Feb 2026#3

Coming back to the opening post, because the follow-up matters more than the original answer.

Two things before anyone answers the substance.

First, the context in the first post is clear and specific. Second, the question is framed so that an answer can actually address it. Both are the norm here and both matter more than they sound.

32 likes 5mo

This topic was referenced in

Washout with a one-week half-life: the arithmetic — does this still hold?Research Methods › N-of-1 designs · 45 replies

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