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  1. #1
    Lounger
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    Trendline with polynomial fit (2000)

    If I have x,y data with a blank cell in the y column I sometimes get a straight line fit even when I request a second order polynomial. This depends on the order of the x,y pairs and the value of x. For example,
    1
    1 1
    2 4
    3 12
    winds up as a straight line where
    1 1
    2 4
    3 12
    1
    or
    4
    1 1
    2 4
    3 12
    result in quadratic equations. Please see attachment for these examples and more. Can anyone explain why?

    Peter

  2. #2
    Plutonium Lounger
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    Re: Trendline with polynomial fit (2000)

    Why do you specify points with x values that overlap others and with empty y values? If you specify points with x values that don't overlap others and with empty y values, you'll just change the scale of the x axis. But overlapping x values confuse Excel.

  3. #3
    Lounger
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    Re: Trendline with polynomial fit (2000)

    Hans,
    Thanks for your reply.
    These were just test cases to try to reproduce a real situation.
    Regards,
    Peter

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