On the subject in the title: Turnaround times and what they mean for a decision — one year on Working notes rather than a conclusion.
Reading back through what has been written here about Turnaround times, three questions come up every time and only one has ever been answered properly.
Listing all three, with what I think the state of the answer is for each, so the thread can start further along than the last one did.
Narrowing post #2, because the general version has more than one answer.
The number people quote for Turnaround times is a central estimate presented without its interval, and the interval is wide enough that the estimate is nearly uninformative on its own.
Reading this Turnaround times thread as someone who came in with a fixed view: the third and seventh replies moved me and the confident ones did not.
The record shows what was measured. Everything beyond that is inference and this site tries to keep the line visible.
I have deliberately not rounded that, because the rounding is where the argument starts.
I would be cautious about generalising from the Turnaround times example above. It is a good example. It is one example.
Post #6 answers the question as asked. The question underneath it is different.
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.
I have separated what I observed from what I concluded, which does not always happen.
Picking up post #6: that is the part I would want checked first.
An observation about Turnaround times that I cannot explain and am posting anyway, on the principle that unexplained observations are more useful public than private.
Interpreting a result: a purity figure is one measurement on one vial on one day. Agreement across two services is much stronger. A single high number does not establish a pattern.
Adding this to the thread rather than to the wiki, because I am not confident enough for the wiki.
Turnaround times came up in a thread eighteen months ago and was answered well. I cannot find it, which is itself the problem, so here is the reconstruction.
Post #11 is the version of this I will quote in future. One addition.
I read the earlier replies on Turnaround times twice before writing this, because I had assumed the opposite and wanted to be sure I was disagreeing with what was said rather than what I expected.
Answering the question post #11 raises rather than the one it answers.
Repeat determination on the same product line months apart is the measurement that speaks to consistency, and consistency is what most buyers actually want.
One of those cases where knowing the mechanism does not help the decision.
A record with four results over sixteen months is a thin record rather than a bad one, and the honest description says which.
Post #11 put the caveat in the right place and I want to underline it.
Reporting rather than recommending, on Turnaround times. What happened is above. Whether it should have is a different question and not one I am qualified to answer.
Cross-checking one lot with two services independently is the cleanest test available and is rarely done because it costs twice as much.
The most useful reply I ever got about Turnaround times was a request to state my units. It sounds like pedantry and it has saved me twice.
Second-hand on Turnaround times, so weight it accordingly — someone whose method I trust told me this and I have not verified it myself.
This follows post #20 rather than contradicting it.
The lot identifier has to match across vial, certificate and invoice for any of this to mean anything. It is the floor and it is worth checking every time.
Saving this. It is the version I will quote when the question comes round again.
Worth separating Turnaround times as a question about the compound from Turnaround times as a question about the documentation. They get answered by different people and only one of them is answerable here.
Small correction to my own earlier position on Turnaround times. I had the units the wrong way round, which changes the conclusion by an order of magnitude and therefore changes it entirely.
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.
On Turnaround times: the maintained page in the documentation commons covers the general case with citations and a review date, which is more reliable than any reply here including this one.
Two things can be true about Turnaround times at once: the mechanism is plausible and the evidence for the size of the effect is thin. Most of the argument here is people defending the first against attacks on the second.
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