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Measurement uncertainty

  1. Nov 11, 2014 #1
    In an attempt to determine how the temperature varies over a distance of 100m, I have taken five temperature measurements for every 10 meters, for a total of 55 measurements. I have then, for each dataset of N=5, calculated the mean value, standard deviation and standard error. Finally, I've plotted the mean value with error bars in what I believe is the most accurate and informative way to represent this data (mean temperature on the y-axis, and distance on the x-axis).

    So far so good I think, but how do I include the accuracy of the, say, 3 1/2 digit measurement equipment if it was specified as accurate to within +/- 5% and +/-3 digits?
     
    Last edited: Nov 11, 2014
  2. jcsd
  3. Nov 11, 2014 #2

    dlgoff

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  4. Nov 11, 2014 #3
    Thanks, but I didn't find what I was looking for at that url.

    What I described above is basically a four step process (measure-->calculate mean-->calculate standard deviation-->calculate standard error) and I'm wondering at what stage it makes the most sense to take the 5% accuracy of the sensor into account. E.g., can I slap it onto the end of said four step process and simply increase the standard error by 5% (I'm guessing not, but I'm asking in order to clarify the problem).
     
  5. Nov 11, 2014 #4

    dlgoff

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    Okay. You want Propagation of Uncertainty.

    This looks good for that: http://www.rit.edu/cos/uphysics/uncertainties/Uncertaintiespart2.html#propagation [Broken]

    from http://www.rit.edu/cos/uphysics/uncertainties/Uncertaintiespart2.html [Broken]
     
    Last edited by a moderator: May 7, 2017
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