The Peptide CommonsEst. May 2024
Independent. We sell nothing and are affiliated with no manufacturer or pharmacy. Every moderation action is logged in public
Evidence · Study critique · continued

Reverse causation in a cohort study of weight and outcome — a second dataset posts 31–60

This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.

SV
s.vukovicTL213 Sep 2025#31
SB
sharps_binTL2Regular13 Sep 2025#32

I read post #30 twice before replying, because I had assumed the opposite.

Choosing the worst interpretation: "The confidence interval includes a harmful effect" is true if the CI goes from -1 to +5. But assuming the worst-case scenario is not how you use the evidence. The point estimate and the precision both matter.

0 likes 10mo
NC
n.cabreraTL2 Moderator13 Sep 2025#33
baseline_peak, post #28: Publication bias: a single published positive trial is weaker evidence than multiple published trials with consistent results. Asking whether there are unpublished negative trials is a fair critical question. Go to post

Defending a paper against criticism: if the authors respond, they might clarify something the paper explained poorly. Their response might also miss your point. Either way, the exchange in public is more useful than quiet disagreement.

0 likes in reply to #28 10mo
SS
steady_stateTL3Regular13 Sep 2025#34
a.nascimento, post #3: Confounding: in observational data, is there a third variable that explains the apparent association? In randomised data, randomisation should balance unknown confounders, though known confounders can be adjusted for. Go to post

Multiple comparisons: if a paper reports many outcomes, the chance of a spurious association by random chance is real. Pre-specification of primary outcomes matters and secondary analyses are weaker evidence.

4 likes in reply to #3 10mo
BK
b.kowalskiTL2 Moderator13 Sep 2025#35

Picking up post #32: that is the part I would want checked first.

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.

13 likes 10mo
JW
journalclub_wrenTL3Regular13 Sep 2025#36

Criticise the method, not the author: a paper with a weak design is not a bad paper by someone with bad intentions. It is a paper that answers a limited question. Sometimes that is what the sponsor wanted, sometimes the researchers did the best they could with constraints.

26 likes 10mo
HA
h.agyemanTL2 Moderator13 Sep 2025 · edited#37
b.kowalski, post #35: Picking up post #32: that is the part I would want checked first. 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… Go to post

Building consensus on which criticisms matter: if everyone agrees that the sample size is small but only you think that affects the conclusion, maybe your criticism is more idiosyncratic. That does not make it wrong but it is worth noticing.

0 likes in reply to #35 10mo
DH
dietitian_hollisTL3Dietitian13 Sep 2025#38

What makes a methodological criticism substantive: it identifies a specific feature of the design that materially affects what the paper can conclude. "Small sample size" alone is weak. "Small sample size for a rare outcome, so the confidence interval is wide" is stronger.

2 likes 10mo
SM
s.mbekiTL2 Moderator13 Sep 2025#39
ma.nascimento, post #20: Bias towards the null and bias away from the null: different criticisms have different directions. Differential dropout might bias away from null; conservative statistical analysis might bias toward null. Go to post

Bias towards the null and bias away from the null: different criticisms have different directions. Differential dropout might bias away from null; conservative statistical analysis might bias toward null.

0 likes in reply to #20 10mo
NA
n.abernathyTL3Analytical chemist13 Sep 2025#40

Building consensus on which criticisms matter: if everyone agrees that the sample size is small but only you think that affects the conclusion, maybe your criticism is more idiosyncratic. That does not make it wrong but it is worth noticing.

0 likes 10mo
YM
y.mensahTL3Wiki editor13 Sep 2025#41

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.

25 likes 10mo
CC
c.castellanosTL2 Moderator13 Sep 2025#42
Wickramasinghe, post #24: Choosing the worst interpretation: "The confidence interval includes a harmful effect" is true if the CI goes from -1 to +5. But assuming the worst-case scenario is not how you use the evidence. The point estimate and the precision both matter. Go to post

Criticise the method, not the author: a paper with a weak design is not a bad paper by someone with bad intentions. It is a paper that answers a limited question. Sometimes that is what the sponsor wanted, sometimes the researchers did the best they could with constraints.

12 likes in reply to #24 10mo
NE
n.ekstromTL2Regular13 Sep 2025 · edited#43

On post #39 — agreed on the reasoning, with one qualification.

Choosing the worst interpretation: "The confidence interval includes a harmful effect" is true if the CI goes from -1 to +5. But assuming the worst-case scenario is not how you use the evidence. The point estimate and the precision both matter.

1 like 10mo
TK
t.karlsenTL2 Moderator13 Sep 2025#44

When you change your mind: if a reply convinces you that your criticism was not well-founded, say so plainly. The critique might still be real but smaller than you originally thought. That is not a failure — it is how discussion works.

0 likes 10mo
SS
steady_stateTL3Regular13 Sep 2025#45

Generalisability: do the inclusion/exclusion criteria narrow the population so much that results do not apply to real people asking about it? This is a fair criticism but requires specificity about which real people and why the difference matters.

18 likes 10mo
YA
y.asanteTL2 Moderator14 Sep 2025#46
d.ndiaye, post #21: Worth separating two things that post #17 runs together. Building consensus on which criticisms matter: if everyone agrees that the sample size is small but only you think that affects the conclusion, maybe your criticism is more idiosyncratic. That does not make it wrong but it is worth noticing. Go to post

Confounding: in observational data, is there a third variable that explains the apparent association? In randomised data, randomisation should balance unknown confounders, though known confounders can be adjusted for.

7 likes in reply to #21 10mo
JW
journalclub_wrenTL3Regular14 Sep 2025#47
IMainwaring, post #11: post #10 answers the question as asked. The question underneath it is different. What makes a methodological criticism substantive: it identifies a specific feature of the design that materially affects what the paper can conclude. "Small sample size" alone is weak. "Small sample size for a rare outcome, so the confidence interval is… Go to post

Worth separating two things that post #43 runs together.

What makes a methodological criticism substantive: it identifies a specific feature of the design that materially affects what the paper can conclude. "Small sample size" alone is weak. "Small sample size for a rare outcome, so the confidence interval is wide" is stronger.

0 likes in reply to #11 10mo
EH
e.halonenTL2 Moderator14 Sep 2025#48

post #47 is right about the mechanism and I think understates the practical bit.

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.

0 likes 10mo
SG
s.grahameTL2Member14 Sep 2025#49

Coming back to post #47, because the follow-up matters more than the original answer.

Bias towards the null and bias away from the null: different criticisms have different directions. Differential dropout might bias away from null; conservative statistical analysis might bias toward null.

12 likes 10mo
ER
e.roosTL2 Moderator14 Sep 2025#50

Picking up post #47: that is the part I would want checked first.

Multiple comparisons: if a paper reports many outcomes, the chance of a spurious association by random chance is real. Pre-specification of primary outcomes matters and secondary analyses are weaker evidence.

4 likes 10mo
EP
e.piresTL2 Moderator14 Sep 2025#51
y.asante, post #46: Confounding: in observational data, is there a third variable that explains the apparent association? In randomised data, randomisation should balance unknown confounders, though known confounders can be adjusted for. Go to post

Defending a paper against criticism: if the authors respond, they might clarify something the paper explained poorly. Their response might also miss your point. Either way, the exchange in public is more useful than quiet disagreement.

0 likes in reply to #46 10mo
FA
f.amankwahTL2 Moderator14 Sep 2025#52

Worth separating two things that post #48 runs together.

Publication bias: a single published positive trial is weaker evidence than multiple published trials with consistent results. Asking whether there are unpublished negative trials is a fair critical question.

3 likes 10mo
HS
hana.satoTL4 Moderator14 Sep 2025#53
Staff post. Actions described here are recorded in the public moderation log and may be challenged in Meta.

Defending a paper against criticism: if the authors respond, they might clarify something the paper explained poorly. Their response might also miss your point. Either way, the exchange in public is more useful than quiet disagreement.

15 likes 10mo
CO
c.ostergaardTL2 Moderator14 Sep 2025#54

Practical note that does not fit anywhere else. Whatever you conclude from this topic, write down what you did and when. The single most useful thing in your own records is not any individual result; it is that they are dated and consecutive.

30 likes 10mo
VB
v.bhattacharyaTL2 Moderator14 Sep 2025#55
t.karlsen, post #44: When you change your mind: if a reply convinces you that your criticism was not well-founded, say so plainly. The critique might still be real but smaller than you originally thought. That is not a failure — it is how discussion works. Go to post

Confounding: in observational data, is there a third variable that explains the apparent association? In randomised data, randomisation should balance unknown confounders, though known confounders can be adjusted for.

1 like in reply to #44 10mo
JD
j.dahlbergTL2 Moderator14 Sep 2025 · edited#56

Generalisability: do the inclusion/exclusion criteria narrow the population so much that results do not apply to real people asking about it? This is a fair criticism but requires specificity about which real people and why the difference matters.

6 likes 10mo
TW
t.wojcikTL2 Moderator14 Sep 2025#57

Picking up post #54: that is the part I would want checked first.

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.

21 likes 10mo
AK
a.kowalskiTL2 Moderator14 Sep 2025#58

Bias towards the null and bias away from the null: different criticisms have different directions. Differential dropout might bias away from null; conservative statistical analysis might bias toward null.

0 likes 10mo
FP
forest_plotTL3Evidence synthesis14 Sep 2025#59

Building consensus on which criticisms matter: if everyone agrees that the sample size is small but only you think that affects the conclusion, maybe your criticism is more idiosyncratic. That does not make it wrong but it is worth noticing.

2 likes 10mo
SA
s.antonsenTL2 Moderator14 Sep 2025#60

Criticise the method, not the author: a paper with a weak design is not a bad paper by someone with bad intentions. It is a paper that answers a limited question. Sometimes that is what the sponsor wanted, sometimes the researchers did the best they could with constraints.

9 likes 10mo