# percent difference

#### hoorayformondays

##### New Member
hi! I have already calculated for the sample means and standard deviation of my data set. For one data set I got 0.0798±0.0004 for the other one I got 0.0798±0.0009. If it proper to say that the percent difference is 0% or would the standard deviation values have an effect on the percent difference? If so, how would I calculate for the percent difference?

#### joeb33050

##### Member
What are the standard deviations? Where do +/- .0004 and .0009 come from? If s is teeny, it may not be proper to say that the percent difference is 0%. If s is huge, it may be proper to say that the percent difference is 0%. As somebody once said, it's all relative.
joe b.

#### hoorayformondays

##### New Member
What are the standard deviations? Where do +/- .0004 and .0009 come from? If s is teeny, it may not be proper to say that the percent difference is 0%. If s is huge, it may be proper to say that the percent difference is 0%. As somebody once said, it's all relative.
joe b.
oh sorry, the 0.0004 and the 0.0009 are the calculated standard deviation values of the dataset

#### joeb33050

##### Member
34Some thoughts:
An s of .0004 means that measurements of .0797 and .0799 were happening, +/- 1 in 10,000. Measurements with a reasonable unit of measure, of about anything, are complex even today. Measurement to .0001" require equipment capable of precision of +/- .00005".
An s of .0004 / mean of .0798 is a coefficient of variation of 1/200 = .005. CV is one of my interests; a CV of some Normal constructions varies with n; with n = 5, CV = .27. I've not run across a CV of .00anything, or of .0anything; and .005 means a production control, by man or God, that is remarkable.
With these numbers, the larger/smaller is 1, at least to .00.
joe b.