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Dataplot Vol 2 Vol 1

DIFFERENCE OF VARIANCE

Name:
    DIFFERENCE OF VARIANCE (LET)
Type:
    Let Subcommand
Purpose:
    Compute the difference between the variances for two response variables.
Description:
    The variance is a common measure of the spread of a distribution or variable. The formula is:

      \( s = \frac{\sum_{i=1}^{n}{(x - \bar{x})^2}}{n-1} \)

    with \( \bar{x} \) denoting the mean.

    For the differeence of variances, the variance is computed for each of two samples then their difference is taken.

Syntax:
    LET <par> = DIFFERENCE OF VARIANCE <y1> <y2>
                            <SUBSET/EXCEPT/FOR qualification>
    where <y1> is the first response variable;
                <y2> is the first response variable;
                <par> is a parameter where the computed difference of the variances is stored;
    and where the <SUBSET/EXCEPT/FOR qualification> is optional.
Examples:
    LET A = DIFFERENCE OF VARIANCE Y1 Y2
    LET A = DIFFERENCE OF VARIANCE Y1 Y2 SUBSET X > 1
Note:
    Dataplot statistics can be used in a number of commands. For details, enter

Default:
    None
Synonyms:
    None
Related Commands: Applications:
    Data Analysis
Implementation Date:
    2003/03
Program:
    SKIP 25 
    READ IRIS.DAT Y1 TO Y4 X 
    . 
    LET A = DIFFERENCE OF VARIANCE Y1 Y2 
    TABULATE DIFFERENCE OF VARIANCE Y1 Y2 X 
    . 
    XTIC OFFSET 0.2 0.2 
    X1LABEL GROUP ID 
    Y1LABEL DIFFERENCE OF VARIANCE 
    CHAR X 
    LINE BLANK 
    DIFFERENCE OF VARIANCE PLOT Y1 Y2 X 
    CHAR X ALL 
    LINE BLANK ALL 
    BOOTSTRAP DIFFERENCE OF VARIANCE PLOT Y1 Y2 X  
        
    Dataplot generated the following output.
           ********************************************
           **  LET A = DIFFERENCE OF VARIANCE Y1 Y2  **
           ********************************************
      
      
     THE COMPUTED VALUE OF THE CONSTANT A             =  0.49571407E+00
      
      
           ***********************************************
           **  TABULATE DIFFERENCE OF VARIANCE Y1 Y2 X  **
           ***********************************************
      
      
                     *    Y1       AND Y2
         X           *    DIFFERENCE OF VARIANCES
     **********************************************
         1.00000     *   -0.194408E-01
         2.00000     *    0.167963
         3.00000     *    0.300339
      
           GROUP-ID AND STATISTIC WRITTEN TO FILE DPST1F.DAT
        
    plot generated by sample program

    plot generated by sample program

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Date created: 03/27/2003
Last updated: 11/12/2015

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