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

The difference of midmeans statistic is also supported for the following commands:
DIFFERENCE OF MIDMEANS PLOT Y1 Y2 X
CROSS TABULATE DIFFERENCE OF MIDMEANS PLOT Y1 Y2 X
BOOTSTRAP DIFFERENCE OF MIDMEANS PLOT Y1 Y2
TABULATE DIFFERENCE OF MIDMEANS Y1 Y2 X
CROSS TABULATE DIFFERENCE OF MIDMEANS Y1 Y2 X
LET Z = CROSS TABULATE DIFFERENCE OF MIDMEANS Y1 Y2 X1 X2


Enter

HELP STATISTIC PLOT
HELP CROSS TABULATE PLOT
HELP BOOTSTRAP PLOT
HELP TABULATE
HELP CROSS TABULATE
HELP CROSS TABULATE (LET)


for more information on these plots and commands.

None

None

MIDMEAN	= Compute the midmean.
DIFFERENCE OF MEAN	= Compute the difference of means.
DIFFERENCE OF TRIMMED MEAN	= Compute the difference of trimmed means.
DIFFERENCE OF MEDIAN	= Compute the difference of medians.
DIFFERENCE OF BIWEIGHT LOCATION	= Compute the difference of biweight locations.
STATISTICS PLOT	= Generate a statistic versus subset plot.
CROSS TABULATE PLOT	= Generate a statistic versus two subsets plot.
BOOTSTRAP PLOT	= Generate a bootstrap plot.

Data Analysis

3/2003

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