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Math Help - Which regression should I use for this data?

  1. #1
    Newbie
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    Jul 2009
    Posts
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    Which regression should I use for this data?

    Hello there,

    I have done a few observations:

    Code:
        x   |   y
    --------+-------
      150   |   7.4
      130   |  11.6
      110   |  18.8
       90   |  33.2
       70   |  61.4
       50   | 120.8
       30   | 239.8
       20   | 335.0
       10   | 453.0
        5   | 518.8
        0   | 587.4
       -5   | 655.2
      -10   | 721.0
      -20   | 833.4
      -30   | 908.8
      -40   | 959.6
    I plotted them in on my calculator and tried all the regressions it could calculate for me. They are: LinReg, QuadReg, CubicReg, QuartReg, ExpReg, PwrReg. None of these could calculate a regression that I thought was close enough for my data.

    What I wanted to ask is either:
    a) If somebody with a better calculator would calculate a really close regression for me, or
    b) let me know of some website where I can do it myself.

    Thank you for your time.

    Kind regards,
    Marius Jonsson
    Last edited by king.oslo; February 15th 2011 at 12:22 AM. Reason: Updating my data
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  2. #2
    Grand Panjandrum
    Joined
    Nov 2005
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    someplace
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    Thanks
    4
    Quote Originally Posted by king.oslo View Post
    Hello there,

    I have done a few observations:

    Code:
        x   |   y
    --------+-------
      150   |    19
      130   |    29
      110   |    47
       90   |    82
       70   |   155
       50   |   322
       30   |   738
       20   |  1167
       10   |  1906
        5   |  2470
        0   |  3240
       -5   |  4280
      -10   |  5720
      -20   | 10540
      -30   | 19140
      -40   | 36600
    I plotted them in on my calculator and tried all the regressions it could calculate for me. They are: LinReg, QuadReg, CubicReg, QuartReg, ExpReg, PwrReg. None of these could calculate a regression that I thought was close enough for my data.

    What I wanted to ask is either:
    a) If somebody with a better calculator would calculate a really close regression for me, or
    b) let me know of some website where I can do it myself.

    Thank you for your time.

    Kind regards,
    Marius Jonsson
    The first question that needs to be asked is: What does this data represent?

    That is it is easier to identify what kind of regression to use if we know what general for the relation between the variables should have.

    You will also find thing easier if you use y'=log(y) as the second variable.

    CB
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  3. #3
    Newbie
    Joined
    Jul 2009
    Posts
    18
    I agree.

    X-column is temperature *C from -40 to +150.
    Y-column is the resistance of a thermistor (an electrical component).

    I would like to make a function so that I can calculate which reistance the termistor will have at say 32*C or 112*C. So the function has to be really close to the observations.M
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