[QUANTITY] Why quantities always have errors
Ed Shaya
Edward.J.Shaya.1 at gsfc.nasa.gov
Tue Nov 18 10:50:02 PST 2003
Need to add to my wish list:
Errors can be given as a fraction or percentage of the value
An Error can be for a value or for all the values.
Errors may be generated by algorithm, as in sqrt(N).
Ed
Ed Shaya wrote:
>
> what things are going to be in the Error before we can know what sort
> of beast it is. We should create a wish list of things that COULD go
> into an Error object. Then we can go over it and strike things that
> are either too rare to bother with or just too complicated. Here is
> my wish list:
>
> positiveError: error bar to the plus side
> negativeError: error bar to the minus side
> Error: for symmetric error bars
> sigma: number of standard deviations that the Error represents
> confidence: percentage confidence level that the Error represents
> distributionFunction: gaussian, laurentzian, hat-function, etc
>
> PgtV: Sometimes error is presented as the probability of exceeding
> the given value
> PltV: or not reaching the given value
>
> And, one may have the entire probability function as the quantity in
> the Error.
>
> All of the above for each of
> randomError: Error resulting from finite precision of the measurement
> systematicError: inaccuracy intoduced by faulty equipment,
> calibration, or technique.
> significantFigures: number of significant digits in the number
>
> We also need to deal with the issue of an upperLimit or lowerLimit,
> [which, by the way, usually does not have an error because it is
> either the error or a measured value plus an error. But, it can have
> an error which is actually the error-on-the-error.]
>
> Ed
>
More information about the dm
mailing list