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.
Everything in post #27 holds. The case it does not cover is the one I have.
Dose equivalence calculator: compounds have different potencies. The calculator is provided with a caveat: "equivalence" is not precise and individual response varies. It is a rough starting point, not a dose prescription.
One more caveat and then I will stop qualifying: the sample selected itself.
Practical note on Validating a calculator against hand: 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.
I disagree with the framing of Validating a calculator against hand above, and I think it is a substantive disagreement rather than a terminological one. Setting out why, so it can be checked.
The reasoning depends on an assumption that is doing a lot of work and is never stated. If the assumption holds, the conclusion follows. I do not think it holds generally.
Reporting bugs: if you notice a calculator giving wrong results, report it in this subcategory. Bugs are fixed when identified.
One case, stated as one case.
Why calculators are not medical advice: they do arithmetic. Medical decisions are not arithmetic. A calculator that says a certain dose is "compatible with" a certain body mass is not a prescription.
I keep a log of this specifically because memory is unreliable about it.
Significant figures in the output should not exceed what the inputs support. A concentration calculated from a nominal vial mass is not known to four decimal places.
Small correction to my own earlier position on Validating a calculator against hand. I had the units the wrong way round, which changes the conclusion by an order of magnitude and therefore changes it entirely.
Post #39 is right about the mechanism and I think understates the practical bit.
Precision and significant figures: the calculators do not round to match your input precision. If you input values to one decimal place, the output might have more. Use significant figures appropriate to your input precision.
Confirming post #40 from a second method, which matters more than confirming it from a second person.
Validating a calculator against hand 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.
Maintaining a calculator means checking the arithmetic against hand-worked cases at each review, not checking that it still loads.
Nothing a calculator produces is medical advice, and a correct calculation on inappropriate inputs is still an inappropriate answer.
Somebody will have a better source than mine, and I hope they post it.
Post #42 describes the usual case. This is about the unusual one.
The calculators maintained on this site are open-source and verifiable. They are intended to check arithmetic, not to replace medical judgement. Using them is optional and they are provided for convenience.
It is worth stating the boring hypothesis before the interesting one.
Unit-conversion tools are only as good as the assumption they make about the syringe. Ask what barrel and what graduation interval it assumed before trusting the units figure.
My position on Validating a calculator against hand is current rather than settled. I have revised it once already and I expect to again, so treat it accordingly.
Picking up post #44: that is the part I would want checked first.
A note on how Validating a calculator against hand gets discussed rather than on Validating a calculator against hand itself: the confident posts get the replies and the careful ones get ignored, and the careful ones have been right more often.
On post #46 — agreed on the reasoning, with one qualification.
Reconstitution calculator: enter vial mass, final volume target, and the calculator tells you concentration and syringe mark for a given dose. Useful for double-checking arithmetic when you are doing it by hand.
The version of Validating a calculator against hand that I was taught turned out to be a teaching simplification. Useful, and not true in the way I had assumed it was.
Taking post #52 at face value and following it one step further.
Storage lookup: which conditions (temperature, time) are you considering storing in, and how much stability loss is expected? The calculator gives a rough estimate based on typical stability data. Not a substitute for your compound's specific stability data.
The number people quote for Validating a calculator against hand is a central estimate presented without its interval, and the interval is wide enough that the estimate is nearly uninformative on its own.
Why calculators are not medical advice: they do arithmetic. Medical decisions are not arithmetic. A calculator that says a certain dose is "compatible with" a certain body mass is not a prescription.
Do the arithmetic by hand the first few times, whatever tool you use afterwards. A calculator with a wrong input gives a confident wrong answer and there is nothing in the interface to tell you.
Take the reasoning and check the arithmetic; I do not always get it right.
Confirming post #57 from a second method, which matters more than confirming it from a second person.
A calculator that shows its working is worth ten that give an answer. The whole value is being able to see which step you disagree with.
That holds under the stated conditions and I have stated them.