SED navigation bar go to SED home page go to Dataplot home page go to NIST home page SED Home Page SED Staff SED Projects SED Products and Publications Search SED Pages
Dataplot Vol 2 Vol 1

DIFFERENCE OF AAD

Name:
    DIFFERENCE OF AAD (LET)
Type:
    Let Subcommand
Purpose:
    Compute the difference between the average absolute deviations (AAD) for two response variables.
Description
    The average absolute deviation is defined as

      \( AAD = \frac{\sum_{i=1}^{n}{|x - \bar{x}|}}{n} \)

    with \( \bar{x} \) denoting the mean of the variable and n denoting the number of observations. This statistic is sometimes used as an alternative to the standard deviation.

    For the difference of average absolute deviations, the average absolute deviation is computed for each of two samples then their difference is taken.

Syntax:
    LET <par> = DIFFERENCE OF AAD <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 average absolute deviations is stored;
    and where the <SUBSET/EXCEPT/FOR qualification> is optional.
Examples:
    LET A = DIFFERENCE OF AAD Y1 Y2
    LET A = DIFFERENCE OF AAD Y1 Y2 SUBSET X > 1
Note:
    Prior to the 2014/07 version, the AVERAGE ABSOLUTE DEVIATION command computed the difference from the median rather than the mean. The 2014/07 version corrected this command to compute differences from the mean and added the command

      AVERAGE ABSOLUTE DEVIATION FROM THE MEDIAN

    to compute differences from the median.

    Since the DIFFERENCE OF AVERAGE ABSOLUTE DEVIATIONS was based on the average absolute deviation computation, these changes apply to it as well.

Note:
    Dataplot statistics can be used in a number of commands. For details, enter

Default:
    None
Synonyms:
    AVERAGE ABSOLUTE DEVIATION is a synonym for AAD.
Related Commands: Applications:
    Data Analysis
Implementation Date:
    3/2002
Program:
    SKIP 25 
    READ IRIS.DAT Y1 TO Y4 X 
    . 
    LET A = DIFFERENCE OF AAD Y1 Y2 
    TABULATE DIFFERENCE OF AAD Y1 Y2 X 
    . 
    XTIC OFFSET 0.2 0.2 
    X1LABEL GROUP ID 
    Y1LABEL DIFFERENCE OF AAD 
    CHAR X 
    LINE BLANK 
    DIFFERENCE OF AAD PLOT Y1 Y2 X 
    CHAR X ALL 
    LINE BLANK ALL 
    BOOTSTRAP DIFFERENCE OF AAD PLOT Y1 Y2 X  
        
    Dataplot generated the following output.
           ***************************************
           **  LET A = DIFFERENCE OF AAD Y1 Y2  **
           ***************************************
      
      
     THE COMPUTED VALUE OF THE CONSTANT A             =  0.35400003E+00
      
      
           ******************************************
           **  TABULATE DIFFERENCE OF AAD Y1 Y2 X  **
           ******************************************
      
      
                     *    Y1       AND Y2
         X           *    DIFFERENCE OF AVERAGE ABSOLUTE
     **********************************************
         1.00000     *   -0.140000E-01
         2.00000     *    0.170000
         3.00000     *    0.254000
      
           GROUP-ID AND STATISTIC WRITTEN TO FILE DPST1F.DAT
        
    plot generated by sample program

    plot generated by sample program

Privacy Policy/Security Notice
Disclaimer | FOIA

NIST is an agency of the U.S. Commerce Department.

Date created: 03/27/2003
Last updated: 11/02/2015

Please email comments on this WWW page to alan.heckert@nist.gov.