DIFFERENCE OF SKEWNESS

DIFFERENCE OF SKEWNESS (LET)

Let Subcommand

Compute the difference between the skewnesss for two response variables.

The skewness measures the lack of symmetry in a response variable. The formula is:

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

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

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

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

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

None

None

SKEWNESS	= Compute the skewness.
MEAN	= Compute the mean.
STANDARD DEVIATION	= Compute the standard deviation.
KURTOSIS	= Compute the kurtosis.
DIFFERENCE OF MEAN	= Compute the difference of means.
DIFFERENCE OF SD	= Compute the difference of standard deviations.
DIFFERENCE OF KURTOSIS	= Compute the difference of kurtosis.
STATISTICS PLOT	= Generate a statistic versus subset plot.
CROSS TABULATE PLOT	= Generate a statistic versus two subsets plot.
BOOTSTRAP PLOT	= Generate a bootstrap plot.
TABULATE	= Perform a tabulation for a specified statistic.
CROSS TABULATE	= Perform a cross tabulation for a specified statistic.

Data Analysis

3/2003

SKIP 25 
READ IRIS.DAT Y1 TO Y4 X 
. 
LET A = DIFFERENCE OF SKEWNESS Y1 Y2 
TABULATE DIFFERENCE OF SKEWNESS Y1 Y2 X 
. 
XTIC OFFSET 0.2 0.2 
X1LABEL GROUP ID 
Y1LABEL DIFFERENCE OF SKEWNESS 
CHAR X 
LINE BLANK 
DIFFERENCE OF SKEWNESS PLOT Y1 Y2 X 
CHAR X ALL 
LINE BLANK ALL 
BOOTSTRAP DIFFERENCE OF SKEWNESS PLOT Y1 Y2 X  
    

Dataplot generated the following output.