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Probability and I have a question about standard deviation.

  1. Feb 8, 2007 #1
    I have a question about standard deviation. If I have a hundred of distance data, how can I use standard deviation to choose a suitble range of the distance. What is the relation between standard deviation graph and my data. I can plot a graph using mean and std of the data, but do not know how to relate that graph to my data.

    Thank You.
     
  2. jcsd
  3. Feb 9, 2007 #2

    HallsofIvy

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    What do YOU mean by "a suitable range"? What do YOU mean by "standard deviation graph"? HOW are you drawing a "graph using mean and std of the data"? A graph of what?

    Perhaps you are trying to decide what range you should use in a graph of your data- TCebyshev's inequality might apply here. The probability that all data are between the mean minus h times the standard deviation and the mean plus h times the standard deviation is 1- 1/h2.
     
  4. Feb 10, 2007 #3
    Thank You very much HallsofIvy
    I used excel to plot the standard normal distribution curve using mean and std of the data. But, I dont know how relate this graph with my data to see the deviation of the data. I want to see what is the deviation of data.Or the propability that the data are in a certain value between the mean.

    Code (Text):

    The probability that all data are between the mean minus h times,1- 1/h2.
     
    What is h?

    tq
     
  5. Feb 11, 2007 #4

    HallsofIvy

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    Exactly what I said it was! h is the number of standard deviations on either side of the mean you are including in your graph.
     
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