[R] Rounding a Measurement to be Consistent with its Uncertainty

[Tom La Bone]

Uwe Ligges-3 wrote:
> 
> 
> 
> Tom La Bone wrote:
>> I have a measurement of 8165.666 and an uncertainty of 338.9741 (the
>> units of
>> both are unimportant). I can easily round the uncertainty to two
>> significant
>> digits with signif(338.9741,2), which gives 340. Is there a function in R
>> that will take 8165.666 and round it to be consistent with its
>> uncertainty,
>> i.e., 8170?
> 
> That's not consistent, you have 3 significant digits here, but 2 for the 
> "uncertainty" (whatever that is) ...
> 
> Uwe Ligges
> 
> 
>> 
>> Tom
> 
> In metrology, what I did is indeed consistent (provided that I have
> correctly interpreted the guidance given in the "ISO Guide to the
> Expression of Uncertainty in Measurement"). The uncertainty is basically a
> way of specifying in which digits I begin to doubt my result. So, I while
> I will usually have two digits in my uncertainty, I can have 10
> significant digits in my result. Some folks have given me some ideas
> off-line on how to write a function that will round a number in this
> fashion, but I always prefer to use an existing R function if it already
> exists rather than write my own. And, with the tens of thousands of R
> functions in existence, it is always a good idea to ask the forum if they
> know of one.
> 
> Tom
> 
> 
> 
> 
> 
> ______________________________________________
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> 
> 

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