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  • area under curve summary

    Thanks to all who replied about determining area under the
    curve with excel data. Here is a summary of responses.

    Charlie Gatt

    ************************************************** ******************
    Consult the following addresses:

    MathSoft
    software: Mathcad 8
    www.mathsoft.com

    and

    Wolfram Research
    software: Mathematica
    www.wolfram.com

    Best Regards,

    Wagner de Godoy
    Gait Laboratory
    AACD - Brazil
    www.aacd.org.br
    ***************************************
    A couple of my PhD students have been using Kaleidagraph with success.

    Yours

    Liz Tanner

    ================================================== =========================
    ==
    Professor K.E. Tanner
    Professor of Biomedical Materials
    IRC in Biomedical Materials and Department of Materials
    Queen Mary and Westfield College
    Mile End Road
    London
    E1 4NS

    phone +44-171-975-5318
    fax +44-181-983-1799
    e-mail K.E.Tanner@qmw.ac.uk
    ****************************************
    I suppose, that you have a certain number of points (lets say n pairs
    (x_i,y_i)) which define your curve. The integral is then defined as

    I = sum( (y_(i+1) + y_i )/2 * ( x_(i+1) - x_i )

    where the sum runs over all points i=1,...,n-1. You should be able to
    define this in Excel yourself.

    Regards

    Martin

    --
    __________________________________________________ _________________________
    ____________
    Dr. Martin Pohl
    Department of Orthopaedic Research and Biomechanics
    Helmholtzstr. 14
    89081 ULM
    Germany, EU
    phone: +49-(0)731-50-23494 FAX: +49-(0)731-50-23498
    WWW: http://pollux.medizin.uni-ulm.de e-mail:
    mailto://martin.pohl@medizin.uni-ulm.de
    ************************************************** ***************
    There is a software which you can download free
    it is called accuROC.

    Chaim Singal
    ************************************************** **************
    Easy, have you got student edition of MATLAB. If so use Trapz function.
    Import x,y series as cols. into matlab using LOAD function.
    N.B. You dont even have to import x series, as long as you know the
    difference between x1,x2 (and it is constant, like time) etc then multiply
    the output of Trapz function by (x2-x1). Do it for each series.

    One problem though, make sure all col. are of sam length as MATLAB imports
    as a matrix (access each col. of matrix in turn). Solution, replace empty
    cells with zeros.

    Simple, I hope. Any questions I had to do this recently. Takes only a few
    minutes.

    Regards
    William Higgs
    Mechanical Engineering
    University of Sydney
    Australia
    ************************************************** ***********
    Just look in any introductory calculus textbook for calculations of
    areas under curves. You could use the trapezoidal approximation,
    Simpson's rule or any other approach. You just calculate the formula
    for two or three cells and copy it down the column. Dead easy.

    Best regards,

    Mike
    J. Michael Lee, Ph.D.
    Interim Director, Biomedical Engineering Programme

    Associate Professor of Biomaterials (902) 494-6734 (Voice)
    Chair, Dept. of Applied Oral Sciences (902) 494-2527 (FAX)
    Dalhousie University
    5981 University Avenue jmlee@is.dal.ca
    Halifax, Nova Scotia (902) 494-2162 Tissue Mechanics Lab
    Canada B3H 3J5 (902) 494-6784 Tissue Structure Lab
    ************************************************** ***********
    BioProc - Software for processing of analog data (contributed by Gordon ERobertson) reads and displays Kistler, APAS and other file formats.
    Includes algorithms for smoothing and ensemble averaging of signals.

    This program is designed to perform many types of processing on data or
    various data or properly formatted ASCII files. There are many different
    ways of integrating in this program, and choosing the most appropriate
    depends on the type of data being used.

    You can download this software from the ISB website. Also, you can download
    the Bioproc manual. Follow the instructions for installation from the ISB
    website. Lastly, you most likely will have to convert your ascii files into
    *.bpa format which will enable Bioproc to read and process you files. This
    is freeware software so you can't go wrong. I use this software for
    processing GRF forces, EMG data and any sort of other data. It is quite a
    powerful tool in your software arsenal.

    Dan
    Dan Ramsey

    Motor Control Laboratory Tel: +46 (8)-517-77-503
    Astrid Lindgren Hospital Fax: +46 (8)-517-77-351
    Karolinska Institute E-mail: Dan.Ramsey@kbh.ki.se
    S-171 76 Stockholm
    Sweden

    Motorlab Homepage: http://ikaros.f1.ki.se/motorlab/index.htm

    Faculty Homepage: http://137.122.122.109/
    ************************************************** ***********
    You can write your own macro to estimate area using something like a
    trapezoidal estimation. Here is the code I use in C (you can adapt it as
    you like).

    /* trapezoidal approximation */
    float t=0;
    flg=5;
    Fs=input("Enter the Frame rate, OR enter -1 if you prefer to
    provide
    interval time: ");
    if(Fs==-1) {
    t=input("Enter interval time: "); }
    else {
    t=1/Fs;
    printf("\nInterval time is %1.5f",t); }
    for(i=0; i
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