Topic summary

Washout with a one-week half-life: the arithmetic

Research Methods › N-of-1 designs effect size data table worked example Wiki

This is a generated summary. It shows the 9 most-liked posts from a topic of 97, in their original order, with the accepted answer included where one exists. It is a reading aid and it will miss nuance — the full topic is the record.

s.kimaniTL2 Moderator20 Nov 2024#1

Community wiki post. Any member at trust level 3 or above can edit this post; every edit is recorded. Last edited by PharmNotes_Whitfield on 27 Apr 2025.

1 Dec 2024 — crossref_check: Plain-language pass on the opening paragraph.
27 Apr 2025 — PharmNotes_Whitfield: Corrected an arithmetic slip in the second example.

Editors: crossref_check, PharmNotes_Whitfield

Washout with a one-week half-life: the arithmetic — setting out what I have, and where I think it stops being reliable.

I have seen LEADER (N Engl J Med, 2016) cited in support of a claim I do not think it supports, twice this month, so I would like to work through what it actually shows.

My reading is that the trial is sound for its own question and is being stretched to answer a different one. I might be wrong about that, which is why this is a topic rather than a correction.

What I would like from this discussion: someone who disagrees with me to say why, with the section of the paper they are relying on.

51 likes 20mo

t.nardoneTL3Regular23 Nov 2024#10

l.chevalier, post #4: Washout periods: after stopping a medication, how long does it take for the effect to wash out? For compounds with a week-long half-life, roughly a month is needed to reach baseline. Using that washout period in a before-after design strengthens the inference. Go to post

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

27 likes in reply to #4 20mo

f.villalobosTL2 Moderator24 Nov 2024#11

Thank you for the correction. I have edited my earlier post with a note rather than silently, so the thread still makes sense to read. The error was mine and it was the kind that comes from remembering a figure instead of looking it up.

29 likes 20mo

f.fenwickTL3Regular26 Nov 2024#20

Coming back to post #18, because the follow-up matters more than the original answer.

Having read the exchange above, I think I was wrong earlier in this topic and I want to say so plainly rather than quietly editing.

The correction was fair and I had been repeating something I had not checked carefully enough.

30 likes 20mo

s.ivaturiTL2 Moderator29 Nov 2024#35

Generalisability: a robust n-of-1 result applies to you. It does not tell you much about whether the effect generalises to others similar to you, much less to people different from you.

29 likes 20mo

trough_indexTL3Regular30 Nov 2024 · edited#41

Sample size in n-of-1: you are the sample. Repeated measurements (weekly weighings, daily mood scores) increase the power to detect a real effect even though n=1.

30 likes 20mo

n.kirchnerTL2 Moderator2 Dec 2024 · edited#50

I disagree with the reply above, and I think the disagreement is substantive rather than terminological.

The distinction being drawn does not survive when you look at the published data for this specific question. I would be glad to be shown wrong on this, because the version I am arguing against is more convenient.

29 likes 20mo

dr_okonkwoTL4 Moderator4 Dec 2024 · edited#62

trough_index, post #41: Sample size in n-of-1: you are the sample. Repeated measurements (weekly weighings, daily mood scores) increase the power to detect a real effect even though n=1. Go to post

Staff post. Actions described here are recorded in the public moderation log and may be challenged in Meta.

Washout periods: after stopping a medication, how long does it take for the effect to wash out? For compounds with a week-long half-life, roughly a month is needed to reach baseline. Using that washout period in a before-after design strengthens the inference.

32 likes in reply to #41 20mo

f.fontaineTL2 Moderator7 Dec 2024#82

taper_file, post #55: Picking up post #52: that is the part I would want checked first. Generalisability: a robust n-of-1 result applies to you. It does not tell you much about whether the effect generalises to others similar to you, much less to people different from you. Go to post

For anyone arriving from a search: the marked solution above is the direct answer, and the replies underneath it add the caveats that make it safe to use.

31 likes in reply to #55 20mo

Read the full topic (97 posts)

This topic was referenced in

Blinding yourself: practical methods and their limits — the long versionResearch Methods › N-of-1 designs · 11 replies

Suggested topics

Topic	Participants	Replies	Views	Activity
An ABAB design with a data table and honest limitations Research Methods › N-of-1 designs effect size confounding worked example 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…		2	45k	5mo
Pre-registering a personal experiment, seriously Research Methods › N-of-1 designs worked example data table effect size confounding Pre-registering a personal experiment, seriously — setting out what I have, and where I think it stops being reliable. Comparing STEP 4 ( JAMA , 2021) with SUSTAIN 6 ( N Engl J Med , 2016) and finding the…	+96	119	58k	14mo
Blinding yourself: practical methods and their limits — the long version Research Methods › N-of-1 designs worked example effect size confounding data table Blinding yourself: practical methods and their limits — the long version Writing it up because I had to work it out twice and would rather nobody else did. I have seen SURMOUNT-OSA ( N Engl J Med , 2024)…	+7	11	1.8k	22h
Coming back to: Why most self-reports here are not experiments, and that is fine Research Methods › N-of-1 designs worked example data table effect size Solved Closed The question in the title: Why most self-reports here are not experiments, and that is fine I will give what I have already checked below so nobody repeats it. Comparing LEADER ( N Engl J Med , 2016) with…	+56	62	11k	4mo
Why most self-reports here are not experiments, and that is fine Research Methods › N-of-1 designs confounding worked example data table effect size Closed Why most self-reports here are not experiments, and that is fine — that is the question, and I have not found it answered plainly anywhere I have looked. I have seen SURPASS-2 ( N Engl J Med , 2021) cited in…		2	46k	11mo

Related topics — sharing the tags effect size, data table, worked example

Topic	Participants	Replies	Views	Activity
Immortal time bias in a claims-database study — one year on Evidence › Study critique effect size risk of bias confounding Solved Posting this under the heading it deserves: Immortal time bias in a claims-database study — one year on Everything below is what sits behind that. Comparing SURPASS-2 ( N Engl J Med , 2021) with SURMOUNT-1 (…	+41	46	3.7k	22h
Washout: how long is long enough, and for what purpose Pharmacology › Pharmacokinetics semaglutide missed dose worked example Closed Washout: how long is long enough, and for what purpose — setting out what I have, and where I think it stops being reliable. A documentation question rather than an analytical one. I have a certificate in…	+63	70	13k	10mo
Revisiting: Semaglutide formulation: what is in the licensed product besides the peptide Compounds › Semaglutide effect size type 2 diabetes randomised trial Solved Posting this under the heading it deserves: Revisiting: Semaglutide formulation: what is in the licensed product besides the peptide Everything below is what sits behind that. I have seen SURMOUNT-4 ( JAMA ,…	+72	77	7.2k	19mo
Trifluoroacetate content and its consequences Analytics › Impurities & related substances water content data table forced degradation counter-ion content Trifluoroacetate content and its consequences — setting out what I have, and where I think it stops being reliable. A documentation question rather than an analytical one. I have a certificate in front of me…	+123	134	31k	5mo
The decimal-point error, and the habit that catches it Practice › Reconstitution syringe units concentration maths worked example bacteriostatic water The decimal-point error, and the habit that catches it Writing it up because I had to work it out twice and would rather nobody else did. Practical question with the units stated, because I have seen how…	+110	121	10k	7mo