DIFFERENCE OF MEAN

DIFFERENCE OF MEAN (LET)

Let Subcommand

Compute the difference between the means for two response variables.

The mean is computed as
\( \bar{x} = \frac{\sum_{i=1}^{n}{x_i}}{n} \)

For the difference 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

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

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.
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 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