The mass-error checker and its intended scope posts 61–90
This is a continuation of a long topic, addressed by post number rather than by page. Start at post 1.
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.
That is one dataset and I would not build a rule on it.
Fine by me. I had wanted a stronger conclusion and there is not one available.
Mass-error checker 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.
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.
I would be interested in a counterexample if anyone has one.
Collapsed as off-topic by two members at trust level 3 or above
Picking up post #69: that is the part I would want checked first.
The failure mode on mass-error checker is boring rather than dramatic. It is almost always the step everyone assumes was done correctly because it is too simple to get wrong.
This follows post #68 rather than contradicting it.
The parts-per-million mass-error calculation is simple enough to do mentally to one significant figure, which is a good habit because it catches an order-of-magnitude slip immediately.
Worth separating two things that post #71 runs together.
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.
Mass-error checker 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.
The number people quote for mass-error checker is a central estimate presented without its interval, and the interval is wide enough that the estimate is nearly uninformative on its own.
This is the sort of exchange that makes the archive worth searching.
Tools that run entirely in the browser send nothing anywhere, which matters more to some people here than others and is worth stating either way.
Not the whole picture, but the part of it I can speak to.
A definition problem is doing most of the work in this mass-error checker discussion. Once the term is pinned down I suspect the disagreement mostly goes away and what is left is small.
What I would check first on mass-error checker is whether the thing being measured moved or whether the way of measuring it moved. Those look identical in a graph.
The most common input error is entering the vial mass in the concentration field. It produces a plausible number, which is why it survives.
Happy to be the one who is wrong here if it settles the question.
The thing about mass-error checker that took me longest to accept is that a plausible mechanism is not evidence of an effect. It is a reason to look, not a result.
Post #79 and I disagree about the size of the effect, not about the direction.
Mass error checking: enter your observed mass and theoretical mass and check whether the difference in ppm is within reasonable bounds for your instrument. Useful sanity check on LC-MS results.
It is worth checking rather than assuming, which costs nothing.
Bookmarking this. I will come back when I have something worth adding.
Filing a mild objection to the consensus on mass-error checker. Mild because I might be wrong; an objection because nobody has addressed the case that does not fit.
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.
This has been discussed before and I could not find the thread, so, again.
Building on post #83 rather than restating it.
Two sentences on mass-error checker and then I will stop, because the rest is speculation and the thread is better without mine.
What is documented is narrow. What is inferred from it is broad. The gap between them is where every argument here lives.
Mass-error checker: I would want to see the raw numbers rather than the summary before agreeing. Summaries lose exactly the information that would settle this.
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.
One caution on mass-error checker: everything above assumes the underlying documentation is what it claims to be. That assumption is doing real work and is rarely stated.