DIFFERENCE OF GEOMETRIC SD

DIFFERENCE OF GEOMETRIC SD (LET)

Let Subcommand

Compute the difference between the geometric standard deviations for two response variables.

The geometric standard deviation is defined as:
\( \mbox{GSD} = e^{sd(\log{X_i})} \)

For the difference of geometric standard deviations, the geometric standard deviation is computed for each of two samples then their difference is taken.

LET <par> = DIFFERENCE OF GEOMETRIC SD <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 geometric standard deviations is stored;
and where the <SUBSET/EXCEPT/FOR qualification> is optional.

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

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

None

None

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

Dataplot generated the following output.

       ************************************************
       **  LET A = DIFFERENCE OF GEOMETRIC SD Y1 Y2  **
       ************************************************
  
  
 THE COMPUTED VALUE OF THE CONSTANT A             = -0.21327734E-02
  
  
       ***************************************************
       **  TABULATE DIFFERENCE OF GEOMETRIC SD Y1 Y2 X  **
       ***************************************************
  
  
                 *    Y1       AND Y2
     X           *    DIFFERENCE OF GEOMETRIC SD
 **********************************************
     1.00000     *   -0.462339E-01
     2.00000     *   -0.331452E-01
     3.00000     *   -0.122206E-01
  
       GROUP-ID AND STATISTIC WRITTEN TO FILE DPST1F.DAT