DIFFERENCE OF MEAN

DIFFERENCE OF MEAN (LET)

Let Subcommand

Compute the difference between the means for two response variables.

The mean is computed as

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

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

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

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

MEAN	= Compute the mean.
DIFFERENCE OF MEDIAN	= Compute the difference of medians.
DIFFERENCE OF TRIMMED MEAN	= Compute the difference of trimmed means.
DIFFERENCE OF MIDMEAN	= Compute the difference of midmeans.
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 MEAN Y1 Y2 
TABULATE DIFFERENCE OF MEAN Y1 Y2 X 
. 
XTIC OFFSET 0.2 0.2
X1LABEL GROUP ID
Y1LABEL DIFFERENCE OF MEANS
CHAR X 
LINE BLANK 
DIFFERENCE OF MEAN PLOT Y1 Y2 X 
CHAR X ALL 
LINE BLANK ALL 
BOOTSTRAP DIFFERENCE OF MEAN PLOT Y1 Y2 X  
    

Dataplot generated the following output.

       ****************************************
       **  LET A = DIFFERENCE OF MEAN Y1 Y2  **
       ****************************************
  
  
 THE COMPUTED VALUE OF THE CONSTANT A             =  0.27860000E+01
  
  
       *******************************************
       **  TABULATE DIFFERENCE OF MEAN Y1 Y2 X  **
       *******************************************
  
  
                 *    Y1       AND Y2
     X           *    DIFFERENCE OF MEANS
 **********************************************
     1.00000     *     1.57800
     2.00000     *     3.16600
     3.00000     *     3.61400
  
       GROUP-ID AND STATISTIC WRITTEN TO FILE DPST1F.DAT