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Research Methods · Statistics · continued

Measurement error in home scales, with a worked standard deviation — the long version posts 31–60

This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1 · go to the accepted answer.

EK
e.kjeldsenTL2Member13 Feb 2026#31
e.ndiaye, post #18: I have no financial interest in anything named in this thread and I want to say so before I comment on Measurement error in home scales, because it is the sort of subject where it matters. Go to post

Relative risk and odds ratios: both compare the rate in one group to the rate in another. Relative risk is easier to understand. Odds ratios are standard in many analyses but can be misinterpreted.

Not a strong opinion, just a consistent one.

5 likes in reply to #18 5mo
PL
p.lindqvistTL214 Feb 2026#32

I changed my mind about Measurement error in home scales after someone here asked me for the source and I could not produce one. That is worth saying out loud because it is the ordinary way it happens.

0 likes 5mo
CE
crossover_entryTL3Regular16 Feb 2026#33

Post #29 and I disagree about the size of the effect, not about the direction.

Bayesian and frequentist analyses answer different questions and both are legitimate. What matters is that the reader knows which is on offer.

0 likes 5mo
BW
br.wikstromTL217 Feb 2026#34

Taking post #33 at face value and following it one step further.

The useful distinction on Measurement error in home scales is between what was measured and what was inferred from it. Both end up in the same sentence and only one of them has error bars.

21 likes 5mo
GR
gradient_reviewTL2Member18 Feb 2026#35
sa.rasmussen, post #24: A standard deviation describes the spread of individuals and a standard error describes the precision of the mean. Quoting one where the other belongs changes the apparent result substantially. Go to post

Source for the Measurement error in home scales figure, since it was asked for. It is in the discussion rather than the abstract, which is why the version circulating is stronger than the paper is.

Reading the surrounding paragraph is worth the two minutes. The authors are more careful than their summarisers.

3 likes in reply to #24 5mo
MM
m.marchettiTL220 Feb 2026 · edited#36

Rounding and significant figures carry information about precision. A figure quoted to four significant figures from a method with two per cent variability is overstating what is known.

0 likes 5mo
MD
methods_draftTL2Member21 Feb 2026#37

Post #33 put the caveat in the right place and I want to underline it.

Practical note on Measurement error in home scales: write down what you expect before you look. The number of times I have found what I went looking for is higher than chance would allow.

29 likes 5mo
KO
k.ogunleyeTL223 Feb 2026#38
s.karlsen_rph, post #1: On the subject in the title: Measurement error in home scales, with a worked standard deviation — the long version Working notes rather than a conclusion. A narrow question about Measurement error in home scales, deliberately narrow, because the broad version has been asked here four times and produced four long threads and no answer.… Go to post

Following this. I have the same question and no better information than the first post.

15 likes in reply to #1 5mo
CD
cannula_driftTL3Regular24 Feb 2026#39

I had written a reply contradicting post #37 and deleted it. Here is what survived.

For anyone finding this later: the short answer on Measurement error in home scales is that it depends on one thing, and the rest of the thread is people identifying which thing.

1 like 5mo
SV
sa.vogelTL225 Feb 2026#40
c.falk, post #6: Where the Measurement error in home scales discussion usually stalls is that nobody wants to say "I do not know" and everyone is willing to say "it varies". Those are the same sentence with different clothes on. Go to post

Confirming post #37 from a second method, which matters more than confirming it from a second person.

Working an example through by hand once makes any of these concepts stick better than reading about them, and the arithmetic is usually a single line.

0 likes in reply to #6 5mo
CN
c.nybergTL227 Feb 2026#41
s.chowdhury, post #27: Where the Measurement error in home scales reasoning breaks down for me is the step from the group result to the individual case. That step is almost never argued for. Go to post

Regression to the mean: if you select people with extreme values (very high or very low), their next measurement is often less extreme just by chance. This can look like a treatment effect when it is just statistics.

2 likes in reply to #27 5mo
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PWendelboeTL1Member28 Feb 2026#42
methods_draft, post #37: Post #33 put the caveat in the right place and I want to underline it. Practical note on Measurement error in home scales: write down what you expect before you look. The number of times I have found what I went looking for is higher than chance would allow. Go to post

Measurement error in home scales is a good example of a question where the honest answer is boring and the interesting answers are unsupported. I would go with boring.

9 likes in reply to #37 5mo
TM
t.marchettiTL21 Mar 2026#43

Adding a small correction to the Measurement error in home scales summary above rather than a disagreement with it. The substance holds; one of the figures is out by a factor that matters.

27 likes 5mo
LS
l.sarkissianTL2Member3 Mar 2026#44

Post #40 describes the usual case. This is about the unusual one.

A standard deviation describes the spread of individuals and a standard error describes the precision of the mean. Quoting one where the other belongs changes the apparent result substantially.

It is worth stating the boring hypothesis before the interesting one.

0 likes 5mo
NR
n.ramosTL24 Mar 2026 · edited#45
formulary_notes, post #25: This is the sort of exchange that makes the archive worth searching. Go to post

Building on post #42 rather than restating it.

On Measurement error in home scales, I would rather understate and be corrected upward than overstate and be quoted. That is a house style here and it is a good one.

5 likes in reply to #25 5mo
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IHollingworthTL2Member5 Mar 2026#46

Whatever the answer on Measurement error in home scales turns out to be, the method for getting there is the same: state the assumption, do the arithmetic in public, invite the correction.

13 likes 5mo
RS
r.sobczakTL27 Mar 2026#47

Confidence intervals: rather than a single point estimate, a range of plausible values. A narrow interval means precise measurement; a wide interval means measurement is imprecise. Wider intervals (more uncertainty) are honest about limitation.

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EA
e.almeidaTL2Member8 Mar 2026#48

One caution on Measurement error in home scales: everything above assumes the underlying documentation is what it claims to be. That assumption is doing real work and is rarely stated.

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ni.kravchenkoTL29 Mar 2026#49
a.nyberg, post #22: Coming back to post #19, because the follow-up matters more than the original answer. A distribution shown is worth ten summary statistics. Where a paper shows individual data points, read those first. A modest claim, modestly supported. Go to post

Taking post #46 at face value and following it one step further.

Two questions I would want answered before drawing anything from the Measurement error in home scales data above: how were the cases selected, and what happened to the ones that dropped out.

0 likes in reply to #22 5mo
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RodriguesTL3Regular11 Mar 2026#50

Post #48 and I disagree about the size of the effect, not about the direction.

Effect sizes: the magnitude of a difference, not just whether it is statistically significant. A difference that is significant (p<0.05) might be too small to matter. A large effect might not be significant if sample size is small.

Written from notes rather than memory, which is why the numbers are specific.

2 likes 5mo
DF
d.fontaineTL212 Mar 2026#51

The most common statistical error in this community is not technical: it is treating a self-selected collection of reports as a sample from a population.

0 likes 5mo
KS
k.salinasTL213 Mar 2026#52

Regression to the mean: if you select people with extreme values (very high or very low), their next measurement is often less extreme just by chance. This can look like a treatment effect when it is just statistics.

0 likes 5mo
K
KLindqvistTL4 Moderator15 Mar 2026 · edited#53

On post #51 — agreed on the reasoning, with one qualification.

Multiple testing inflates the false-positive rate in a way that is entirely predictable and entirely correctable. The correction should be declared in advance.

One of those cases where knowing the mechanism does not help the decision.

13 likes 4mo
IB
i.bakkenTL216 Mar 2026#54
c.nyberg, post #41: Regression to the mean: if you select people with extreme values (very high or very low), their next measurement is often less extreme just by chance. This can look like a treatment effect when it is just statistics. Go to post

Thank you for taking the time. That was more work than a reply usually is.

4 likes in reply to #41 4mo
SK
s.karlsen_rphTL317 Mar 2026#55
KL
k.laurentTL218 Mar 2026#56

Confirming post #53 from a second method, which matters more than confirming it from a second person.

Survivorship in a self-reporting population biases every aggregate produced from it, and the bias is in the flattering direction.

Two people can read the same figure differently here and both be reasonable.

27 likes 4mo
VS
v.szaboTL3Analytical chemist20 Mar 2026#57

Post #56 describes the usual case. This is about the unusual one.

The most useful reply I ever got about Measurement error in home scales was a request to state my units. It sounds like pedantry and it has saved me twice.

8 likes 4mo
OV
o.vukovicTL221 Mar 2026#58

Least significant change is the concept that makes measurement precision usable. Below it, a difference between two readings is not distinguishable from noise.

Written quickly, so the reasoning may be tighter than the wording.

2 likes 4mo
AF
a.finnegan_rdTL2Dietitian22 Mar 2026#59
policy_reader, post #19: Relative risk and odds ratios: both compare the rate in one group to the rate in another. Relative risk is easier to understand. Odds ratios are standard in many analyses but can be misinterpreted. The variance between people here is larger than the effect being discussed. Go to post

Where I part company with post #56, and it is a narrow parting.

Number needed to treat: how many people need to be treated to prevent one bad outcome or achieve one good outcome. More intuitive than relative risk reduction.

Flagging that the sources on this are thinner than the confidence in the thread suggests.

4 likes in reply to #19 4mo
VK
v.kirchnerTL223 Mar 2026#60

Post #59 is the version of this I will quote in future. One addition.

If you are new and reading this thread for the answer to Measurement error in home scales: the answer is conditional, the conditions are in the third reply, and the rest of the thread is worth skipping.

0 likes 4mo