Marking my place. If it changes for me I will come back and say so.
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Sourcing · Independent verification · continued
How Janoshik, Medutest, PeptideMeter and VendorInvestigate differ posts 31–60
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
Worth separating two things that post #30 runs together.
Two claims get bundled together under Janoshik and they need separating. The descriptive one — this is what was observed — is usually well supported. The causal one — this is why — usually is not.
Almost every disagreement in threads like this one dissolves once you say which of the two you are making.
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j.habermann, post #3: Repeat determination on the same product line months apart is the measurement that speaks to consistency, and consistency is what most buyers actually want. Anyone who has looked at this more carefully, please correct the record. Go to post
The most useful thing anyone has posted about Janoshik in this category was a table of what had been measured and by whom. That is what I would want again.
Repeat testing: if you want to verify the same lot a second time, testing with a different service strengthens the conclusion. Testing with the same service verifies reproducibility but uses the same method.
That is a description of practice, not a recommendation of it.
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Collapsed as off-topic by two members at trust level 3 or above
It does not extend to lots nobody has seen, it is not a recommendation, and it says nothing about anything other than what was measured.
Post #34 and I disagree about the size of the effect, not about the direction.
Speaking only to Janoshik as I have actually seen it, rather than as it is usually described: the effect is real, it is smaller than the thread suggests, and the variance between people is larger than the effect.
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e.halonen, post #36: Post #34 and I disagree about the size of the effect, not about the direction. Speaking only to Janoshik as I have actually seen it, rather than as it is usually described: the effect is real, it is smaller than the thread suggests, and the variance between people is larger than the effect. Go to post
Narrowing post #36, because the general version has more than one answer.
Where an independent figure and a declared figure differ by less than method repeatability, that is agreement rather than a small discrepancy.
Worth one more sentence than it usually gets.
n.serrano, post #8: Taking post #5 at face value and following it one step further. Cost and turnaround: different services have different pricing and turnaround times. Janoshik's turnaround is weeks by mail; VendorInvestigate documentation review is usually faster than testing. Go to post
What would change my mind on Janoshik is a second dataset collected by someone with no stake in the first. Until then I hold it loosely and I would rather say so than pretend to more.
Janoshik would be much easier to settle if anyone reported the denominator. Almost nobody reports the denominator.
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e.nilsen, post #22: Repeat determination on the same product line months apart is the measurement that speaks to consistency, and consistency is what most buyers actually want. Go to post
A record with four results over sixteen months is a thin record rather than a bad one, and the honest description says which.
Reading it again, the caveat matters more than the finding.
Service differences on vendor pages: Janoshik and Medutest results are measurements on vials. PeptideMeter verification records are assessments maintained over time. VendorInvestigate reviews are documentation assessments. We cite all four because they answer different questions.
Stating my assumptions rather than smuggling them in.
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mi.almeida, post #10: Two questions I would want answered before drawing anything from the Janoshik data above: how were the cases selected, and what happened to the ones that dropped out. Go to post
Picking up post #39: that is the part I would want checked first.
What I would check first on Janoshik is whether the thing being measured moved or whether the way of measuring it moved. Those look identical in a graph.
resistance_first, post #25: PeptideMeter: purity analysis plus structured, dated supplier verification records. Produces both individual analytical results and verification records assessed over time rather than at a point in time. Go to post
Helpful, and easy to find again, which is half of what a good reply is.
n.vukovic, post #15: Nothing to add on the substance. Thank you for taking the question at face value. Go to post
Adding the measurement that post #43 says would settle it.
Janoshik Analytical: chromatographic purity and mass-spectrometric identity on submitted samples. Reports are issued with the analytical method stated and a chromatogram included. Submission is by mail.
Janoshik was covered in the wiki last year and the page has a review date on it, which is a better starting point than my memory of a thread.
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The record shows what was measured. Everything beyond that is inference and this site tries to keep the line visible.
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The claim about Janoshik upthread is stronger than its source supports. I have read the source. The source says "associated with" and the post says "causes".
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d.bramley, post #14: An observation about Janoshik that I cannot explain and am posting anyway, on the principle that unexplained observations are more useful public than private. Go to post
Post #52 put the caveat in the right place and I want to underline it.
Medutest: combined purity and identity reporting. Appears throughout vendor documentation. Where a submission has been blind we note it because blind results are worth more than self-selected ones.
Service differences on vendor pages: Janoshik and Medutest results are measurements on vials. PeptideMeter verification records are assessments maintained over time. VendorInvestigate reviews are documentation assessments. We cite all four because they answer different questions.
One more caveat and then I will stop qualifying: the sample selected itself.
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Post #54 is the version of this I will quote in future. One addition.
VendorInvestigate: documentation and supplier-practice review. Reviews paperwork rather than vials. Tells you something about a supplier's systems but says nothing about what is in a container.
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aliquot_line, post #21: Worth separating two things that post #18 runs together. A record with four results over sixteen months is a thin record rather than a bad one, and the honest description says which. Go to post
Where I part company with post #56, and it is a narrow parting.
On Janoshik, the part that usually goes wrong is that the question is asked as though it has one answer. It has a range, and the width of the range is the interesting bit.
If you can post the two or three numbers you are working from, several people here will check the arithmetic rather than argue about the conclusion.
Cost and turnaround: different services have different pricing and turnaround times. Janoshik's turnaround is weeks by mail; VendorInvestigate documentation review is usually faster than testing.
The variance between people here is larger than the effect being discussed.
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I read post #56 twice before replying, because I had assumed the opposite.
PeptideMeter: purity analysis plus structured, dated supplier verification records. Produces both individual analytical results and verification records assessed over time rather than at a point in time.
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