DIFFERENCE OF MIDMEAN

DIFFERENCE OF MIDMEAN (LET)

Let Subcommand

Compute the difference between the midmeans for two response variables.

The midmean of a variable is the mean of the observations between the 25th and 75th percentiles. It is sometimes used instead of the mean because it is more resistant to outliers.

For the difference of midmeans, the midmean is computed for two samples and then their difference is taken.

LET <par> = DIFFERENCE OF MIDMEAN <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 midmeans is stored;
and where the <SUBSET/EXCEPT/FOR qualification> is optional.

LET A = DIFFERENCE OF MIDMEAN Y1 Y2
LET A = DIFFERENCE OF MIDMEAN Y1 Y2 SUBSET X > 1

Dataplot statistics can be used in a number of commands. For details, enter
HELP STATISTICS

None

None

MIDMEAN	= Compute the midmean.
MEAN	= Compute the mean.
DIFFERENCE OF MEAN	= Compute the difference of means.
DIFFERENCE OF MEDIAN	= Compute the difference of medians.
DIFFERENCE OF TRIMMED MEAN	= Compute the difference of trimmed means.
DIFFERENCE OF BIWEIGHT LOCATION	= Compute the difference of biweight locations.
STATISTICS PLOT	= Generate a statistic versus subset plot.
BOOTSTRAP PLOT	= Generate a bootstrap plot.
TABULATE	= Perform a tabulation for a specified statistic.

Data Analysis

2003/03

SKIP 25 
READ IRIS.DAT Y1 TO Y4 X 
. 
LET A = DIFFERENCE OF MIDMEAN Y1 Y2 
TABULATE DIFFERENCE OF MIDMEAN Y1 Y2 X 
. 
XTIC OFFSET 0.2 0.2
X1LABEL GROUP ID
Y1LABEL DIFFERENCE OF MIDMEANS
CHAR X 
LINE BLANK 
DIFFERENCE OF MIDMEAN PLOT Y1 Y2 X 
CHAR X ALL 
LINE BLANK ALL 
BOOTSTRAP DIFFERENCE OF MIDMEAN PLOT Y1 Y2 X  
    

Dataplot generated the following output.

       *******************************************
       **  LET A = DIFFERENCE OF MIDMEAN Y1 Y2  **
       *******************************************
  
  
 THE COMPUTED VALUE OF THE CONSTANT A             =  0.29644735E+01
  
  
       **********************************************
       **  TABULATE DIFFERENCE OF MIDMEAN Y1 Y2 X  **
       **********************************************
  
  
                 *    Y1       AND Y2
     X           *    DIFFERENCE OF MIDMEANS
 **********************************************
     1.00000     *     1.60385
     2.00000     *     3.28462
     3.00000     *     3.70769
  
       GROUP-ID AND STATISTIC WRITTEN TO FILE DPST1F.DAT