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Normalising a graph

  1. Feb 11, 2013 #1
    Dear all ,

    Thank you for any help in advance.

    I have a graph in Excel which represents counts (photons) vs pixel i.e distance. This is from a cross sectional profile of an X-ray image.

    I would like to normalise my graph with respect to my background. I have attached the graph. I know I have to draw a best fit line on my background and find the equation but a step by step process would be relly helpful.

    Thank you
     

    Attached Files:

  2. jcsd
  3. Feb 11, 2013 #2

    Simon Bridge

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    Welcome to PF;
    It is tricky to figure what you want because you say "normalize" at first, then you want "best fit line" later... which is it?
    It would have help if you showed us what you have tried or how you are thinking about what is needed.
    Anyway - off your post, I can suggest the following howto's. You can tell us which was right for you, and, if you get stuck, where.

    Single-line 'best fit" method.
    http://serc.carleton.edu/mathyouneed/graphing/bestfit.html

    Crossed lines method - good if you need uncertainties.
    http://www.schoolphysics.co.uk/age16-19/General/text/Uncertainties_in_graphs/index.html

    Normalizing curves in excel;
    http://www.ehow.com/how_12167214_normalize-curves-excel.html [Broken]
     
    Last edited by a moderator: May 6, 2017
  4. Feb 13, 2013 #3

    ssd

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    This appears to be an incomplete Beta function. You have to find its parameters from data, setting the truncation value ahead from experience. Normalization means subtraction of mean from the values and then division by sd.
     
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