3. Reports and Graphics › 3.3 Statistical Analyses › 3.3.5 Descriptive Statistics Report

3.3.5 Descriptive Statistics Report

The Descriptive Statistics Report shows basic descriptive
statistics for numeric variables and some statistics on
missing values.  The descriptive statistics listed below are
available on the report.  It is often used in initial
analysis of workload parameters.

For example, a study of IMS transaction sizes might be
initiated by requesting a descriptive statistics report on
transaction CPU time.  This would provide an overview of the
distribution of transaction sizes and might indicate the
presence of logical groups of similar transactions.

Descriptive statistics included on this report are:

o  Name of the variable
o  Number of observations
o  Sum of the weights of the observations
o  Sum of the observations
o  Mean
o  Standard deviation
o  Variance
o  Skewness
o  Kurtosis
o  Uncorrected sum of squares
o  Corrected sum of squares
o  Coefficient of variation
o  Standard error of the mean
o  Student's t value
o  Probability of a greater absolute value for student's t
o  Approximation of the probability of a greater absolute
   value for student's t if the population mean is 0
o  Number of nonzero observations
o  Largest value
o  Smallest value
o  Range
o  Difference between the upper and lower quartile
o  Mode
o  Quartiles
o  First, 5th, 10th, 90th, 95th, and 99th percentiles
o  Five lowest and highest observations

Figure 3-23 is a sample descriptive statistics report on
average CPU time per CICS transaction.

To create a descriptive statistics report, select the
Descriptive Statistics Report option from either of the
following menus:

o  Direct Inquiry Statistical Analysis Menu
o  Structured Inquiry Statistical Analysis Menu

                             UNIVARIATE

         VARIABLE=CSYAVCPU       AVG. CPU TIME/TRANSACTION


                              MOMENTS

             N               3638  SUM WGTS        3638
             MEAN       0.0976531  SUM          355.262
             STD DEV     0.227644  VARIANCE   0.0518219
             SKEWNESS     13.0746  KURTOSIS     236.044
             USS          223.169  CSS          188.476
             CV           233.115  STD MEAN   0.0037742
             T:MEAN=0     25.8738  PROB>|T|      0.0001
             SGN RANK     3309671  PROB>|S|      0.0001
             NUM .= 0        3638
             D:NORMAL     0.34808  PROB>D          <.01


            QUANTILES(DEF=4)                                   EXTREMES

100% MAX     5.4784     99%     0.496393                     LOWEST    HIGHEST
 75% Q3   0.0868462     95%     0.496393                 0.00875575   0.335454
 50% MED  0.0457787     90%     0.214068                  0.0126819   0.496393
 25% Q1   0.0317973     10%    0.0149672                  0.0149672    1.93864
  0% MIN 0.00875575      5%   0.00875575                   0.019176    4.18481
                         1%   0.00875575                  0.0238682     5.4784
 RANGE      5.46964
 Q3-Q1     0.055049
 MODE     0.0317973

Figure 3-23.  Sample Descriptive Statistics Report