DIFFERENCE OF SD OF THE MEAN

DIFFERENCE OF SD OF THE MEAN (LET)

Let Subcommand

Compute the difference between the standard deviation of the means for two response variables.

The standard deviation of the mean is:
\( s_{mean} = \frac{s}{\sqrt{n}} \)

with s and n denoting the standard deviation and the number of observations, respectively.

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

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

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

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

None

DIFFERENCE OF STANDARD DEVIATION OF THE MEAN is synonym for DIFFERENCE OF SD OF THE MEAN.

SD OF THE MEAN	= Compute the sd of the mean.
STANDARD DEVIATION	= Compute the standard deviation.
MEAN	= Compute the mean.
DIFFERENCE OF MEAN	= Compute the difference of the means.
DIFFERENCE OF SD	= Compute the difference of standard deviations.
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 SD OF THE MEAN Y1 Y2 
TABULATE DIFFERENCE OF SD OF THE MEAN Y1 Y2 X 
. 
XTIC OFFSET 0.2 0.2 
X1LABEL GROUP ID 
Y1LABEL DIFFERENCE OF SD OF THE MEAN 
CHAR X 
LINE BLANK 
DIFFERENCE OF SD OF THE MEAN PLOT Y1 Y2 X 
CHAR X ALL 
LINE BLANK ALL 
BOOTSTRAP DIFFERENCE OF SD OF THE MEAN PLOT Y1 Y2 X  
    

Dataplot generated the following output.

       **************************************************
       **  LET A = DIFFERENCE OF SD OF THE MEAN Y1 Y2  **
       **************************************************
  
  
 THE COMPUTED VALUE OF THE CONSTANT A             =  0.32022983E-01
  
  
       *****************************************************
       **  TABULATE DIFFERENCE OF SD OF THE MEAN Y1 Y2 X  **
       *****************************************************
  
  
                 *    Y1       AND Y2
     X           *    DIFFERENCE OF SD OF THE MEAN
 **********************************************
     1.00000     *   -0.375823E-02
     2.00000     *    0.286198E-01
     3.00000     *    0.443190E-01
  
       GROUP-ID AND STATISTIC WRITTEN TO FILE DPST1F.DAT