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Determining appropriate range from test data

  1. Sep 23, 2012 #1
    Hello all.

    I am performing chemistry experiments and recording the times of various observed results. What I am doing currently is performing the test several times in order to determine what result is "normal."

    My goal is to determine a range as a standard by which all future tests will be compared against. I do not know the correct expected time for these results; this will be set by my experiments.

    Say for example we use this test data in seconds:


    The full range of data is 22 to 27 with the average being 25, But maybe the "acceptable" range should be 25-27.

    I would like to know what tools I should use to analyze this data to determine statistically what range of data should be considered normal.

    Thank you.
  2. jcsd
  3. Sep 23, 2012 #2


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    Science Advisor

    Hey ChaoticLlama.

    One thing you can do is to use a distribution (i.e. a statistical one based on your sample, or if you make an assumption on the population), and look at the interval corresponding to the a/2 in each tail where 1-a corresponds to the probability that defines your interval.

    A lot of people would use a normal distribution and then find the 95% interval for that distribution, but this isn't always right since not everything is always just the "default".
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