The decimal-point error, and the habit that catches it Writing it up because I had to work it out twice and would rather nobody else did.
An honest uncertainty about decimal-point error rather than a disguised assertion.
I do not know the answer and I have not been able to find one. What I have is the shape of the question, which may be worth more than my guess at the answer.
Reading this decimal-point error thread as someone who came in with a fixed view: the third and seventh replies moved me and the confident ones did not.
The opening post is right about the mechanism and I think understates the practical bit.
The decimal-point error: computing 5 mg / 2 mL as 0.25 mg/mL instead of 2.5 mg/mL is the most common arithmetic error in this subcategory. The habit that catches it: writing the units in every step of the calculation.
The confident answers on decimal-point error and the well-sourced answers are not the same answers, which is the most useful thing I have learned reading this category.
Adding the boring version of decimal-point error, because the interesting version keeps getting posted and the boring one is usually right.
Check the ordinary explanations, in order, and stop when one of them accounts for what you are seeing. Most of the time the second one does.
I read post #5 twice before replying, because I had assumed the opposite.
Do not shake. Swirl, or leave it. Vigorous agitation introduces air and shear, and neither helps a peptide go into solution any faster than patience does.
Post #5 answers the question as asked. The question underneath it is different.
Preservative effectiveness is tested against a defined microbial challenge under defined conditions. It is not a licence to treat an entered vial as sterile indefinitely, and no supplier claims otherwise.
This is the sort of thing the wiki should carry and currently does not.
Write the reconstitution date and the concentration on the vial. Not on a note, on the vial. Every account here of a dosing error involving the wrong concentration involves a vial with nothing written on it.
A partial answer, offered because a partial answer beats none.
Summarising the decimal-point error thread so far, since it is long and the answer is buried: the first reply has the method, the fourth has the correction to it, and the rest is people agreeing at length.
What I can speak to on decimal-point error is narrow, so I will keep it narrow rather than generalising from it. Beyond that boundary I do not know.
Do not shake. Swirl, or leave it. Vigorous agitation introduces air and shear, and neither helps a peptide go into solution any faster than patience does.
I am describing what is, rather than arguing for what should be.
Preservative effectiveness is tested against a defined microbial challenge under defined conditions. It is not a licence to treat an entered vial as sterile indefinitely, and no supplier claims otherwise.
Worth checking against a second source before it gets quoted onward.
Decimal-point error is a question about a distribution, not about a value, and treating it as a value is what produces the confident wrong answers.
Taking post #14 at face value and following it one step further.
I would call the community position on decimal-point error likely rather than established, and I would be comfortable defending that hedge.
Post #16 and I disagree about the size of the effect, not about the direction.
Do not shake. Swirl, or leave it. Vigorous agitation introduces air and shear, and neither helps a peptide go into solution any faster than patience does.
That is my reading. Someone else read the same page differently and was reasonable.
Post #17 answers the question as asked. The question underneath it is different.
The honest answer on decimal-point error is that it depends, and the useful part is the list of what it depends on. Four items, in rough order of how much they matter.
Most people get the first two right and then argue about the fourth.
I read post #16 twice before replying, because I had assumed the opposite.
Preservative effectiveness is tested against a defined microbial challenge under defined conditions. It is not a licence to treat an entered vial as sterile indefinitely, and no supplier claims otherwise.
It reads as pedantry until the day it does not.
If you are new and reading this thread for the answer to decimal-point error: the answer is conditional, the conditions are in the third reply, and the rest of the thread is worth skipping.
Where the decimal-point error 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.
Following, with nothing to contribute beyond having asked the same thing elsewhere.
Post #21 is right about the mechanism and I think understates the practical bit.
Do not shake. Swirl, or leave it. Vigorous agitation introduces air and shear, and neither helps a peptide go into solution any faster than patience does.
I would not lead a decision with this, but I would not ignore it either.
Taking post #25 at face value and following it one step further.
A note on how decimal-point error gets discussed rather than on decimal-point error itself: the confident posts get the replies and the careful ones get ignored, and the careful ones have been right more often.
I read post #25 twice before replying, because I had assumed the opposite.
The arithmetic on decimal-point error is the easy part and it is where the errors are, which is an uncomfortable combination. Show your working and someone will catch it.
Preservative effectiveness is tested against a defined microbial challenge under defined conditions. It is not a licence to treat an entered vial as sterile indefinitely, and no supplier claims otherwise.
I checked the source rather than the summary, and they differ.
Post #25 describes the usual case. This is about the unusual one.
I read the earlier replies on decimal-point error 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.
Adding the measurement that post #29 says would settle it.
The decimal-point error: computing 5 mg / 2 mL as 0.25 mg/mL instead of 2.5 mg/mL is the most common arithmetic error in this subcategory. The habit that catches it: writing the units in every step of the calculation.
This is where my knowledge stops and I would rather mark the edge than blur it.