DBMS_STAT

176 DBMS_STAT_FUNCS

The DBMS_STAT_FUNCS package provides statistical functions.

This chapter contains the following topic:

Summary of DBMS_STAT_FUNCS Subprograms

176.1 Summary of DBMS_STAT_FUNCS Subprograms

This table lists and briefly describes the DBMS_STAT_FUNCS subprograms.

Table 176-1 DBMS_STAT_FUNCS Package Subprograms

Subprogram	Description
EXPONENTIAL_DIST_FIT Procedure	Tests how well a sample of values fits an exponential distribution
NORMAL_DIST_FIT Procedure	Tests how well a sample of values fits a normal distribution
POISSON_DIST_FIT Procedure	Tests how well a sample of values fits a Poisson distribution
SUMMARY Procedure	Summarizes a numerical column of a table
UNIFORM_DIST_FIT Procedure	Tests how well a sample of values fits a uniform distribution
WEIBULL_DIST_FIT Procedure	Tests how well a sample of values fits a Weibull distribution

176.1.1 EXPONENTIAL_DIST_FIT Procedure

This procedure tests how well a sample of values fits an exponential distribution.

Syntax

DBMS_STAT_FUNCS.EXPONENTIAL_DIST_FIT (
   ownername    IN    VARCHAR2,
   tablename    IN    VARCHAR2,
   columnname   IN    VARCHAR2,
   test_type    IN    VARCHAR2 DEFAULT 'KOLMOGOROV_SMIRNOV',
   lambda       IN    NUMBER,
   mu           IN    NUMBER,
   sig          OUT   NUMBER);

Parameters

Table 176-2 EXPONENTIAL_DIST_FIT Procedure Parameters

Parameter	Description
`ownername`	The schema where the table resides.
`tablename`	The table where the column resides.
`columnname`	The column of the table against which to run the test.
`test_type`	The type of test to use: '`CHI_SQUARED'`, '`KOLMOGOROV_SMIRNOV'` or '`ANDERSON_DARLING'`.
`lambda`	The scale parameter.
`mu`	The location parameter.
`sig`	The goodness of fit value, based on test type. A small value indicates a significant difference between the sample and the exponential distribution. A number close to 1 indicates a close match.

176.1.2 NORMAL_DIST_FIT Procedure

This procedure tests how well a sample of values fits a normal distribution.

Syntax

DBMS_STAT_FUNCS.NORMAL_DIST_FIT (
   ownername    IN    VARCHAR2,
   tablename    IN    VARCHAR2,
   columnname   IN    VARCHAR2,
   test_type    IN    VARCHAR2 DEFAULT 'SHAPIRO_WILKS',
   mean         IN    NUMBER,
   stdev        IN    NUMBER,
   sig          OUT   NUMBER);

Parameters

Table 176-3 NORMAL_DIST_FIT Procedure Parameters

Parameter	Description
`ownername`	The schema where the table resides.
`tablename`	The table where the column resides.
`columnname`	The column of the table against which to run the test.
`test_type`	The type of test to use: '`CHI_SQUARED'`, '`KOLMOGOROV_SMIRNOV'`, '`ANDERSON_DARLING'` or '`SHAPIRO_WILKS`'.
`mean`	The mean of the distribution against which to compare.
`stdev`	The standard deviation of the distribution against which to compare.
`sig`	The goodness of fit value, based on test type. A small value indicates a significant difference between the sample and the normal distribution. A number close to 1 indicates a close match.

176.1.3 POISSON_DIST_FIT Procedure

This procedure tests how well a sample of values fits a Poisson distribution.

Syntax

DBMS_STAT_FUNCS.POISSON_DIST_FIT (
   ownername    IN    VARCHAR2,
   tablename    IN    VARCHAR2,
   columnname   IN    VARCHAR2,
   test_type    IN    VARCHAR2 DEFAULT 'KOLMOGOROV_SMIRNOV',
   lambda       IN    NUMBER,
   sig          OUT   NUMBER);

Parameters

Table 176-4 POISSON_DIST_FIT Procedure Parameters

Parameter	Description
`ownername`	The schema where the table resides.
`tablename`	The table where the column resides.
`columnname`	The column of the table against which to run the test.
`test_type`	The type of test to use: '`KOLMOGOROV_SMIRNOV'` or '`ANDERSON_DARLING'`.
`lambda`	The lambda parameter is the shape parameter.
`sig`	The goodness of fit value, based on test type. A small value indicates a significant difference between the sample and the Poisson distribution. A number close to 1 indicates a close match.

176.1.4 SUMMARY Procedure

This procedure summarizes the numerical column specified in the columnname of tablename.

The summary is returned as a Summary Type. Note that most of the output of SUMMARY can be obtained with currently available SQL.

Syntax

DBMS_STAT_FUNCS.SUMMARY (
   ownername    IN    VARCHAR2,
   tablename    IN    VARCHAR2,
   columnname   IN    VARCHAR2,
   sigma_value  IN    NUMBER DEFAULT 3,
   s           OUT    SummaryType);

Parameters

Table 176-5 SUMMARY Procedure Parameters

Parameter	Description
`ownername`	The schema where the table resides.
`tablename`	The table where the column resides.
`columnname`	The column of the table to be summarized.
`sigma_value`	The number of sigmas for the set of extreme values, defaults to 3.
`s`	The Record containing summary information about given column.

Definition of SummaryType

TYPE n_arr IS VARRAY(5) of NUMBER;
TYPE num_table IS TABLE of NUMBER;
TYPE summaryType IS RECORD (
   count             NUMBER,
   min               NUMBER,
   max               NUMBER,
   range             NUMBER,
   mean              NUMBER,
   cmode             num_table,
   variance          NUMBER,
   stddev            NUMBER,
   quantile_5        NUMBER,
   quantile_25       NUMBER,
   median            NUMBER,
   quantile_75       NUMBER,
   quantile_95       NUMBER,
   plus_x_sigma      NUMBER,
   minus_x_sigma     NUMBER,
   extreme_values    num_table,
   top_5_values      n_arr,
   bottom_5_values   n_arr);

176.1.5 UNIFORM_DIST_FIT Procedure

This procedure tests well a sample of values fits a uniform distribution.

Syntax

DBMS_STAT_FUNCS.UNIFORM_DIST_FIT (
   ownername    IN    VARCHAR2,
   tablename    IN    VARCHAR2,
   columnname   IN    VARCHAR2,
   var_type     IN    VARCHAR2 DEFAULT 'CONTINUOUS',
   test_type    IN    VARCHAR2 DEFAULT 'KOLMOGOROV_SMIRNOV',
   paramA       IN    NUMBER,
   paramB       IN    NUMBER,
   sig          OUT   NUMBER);

Parameters

Table 176-6 UNIFORM_DIST_FIT Procedure Parameters

Parameter	Description
`ownername`	The schema where the table resides.
`tablename`	The table where the column resides.
`columnname`	The column of the table against which to run the test.
`var_type`	The type of distribution: '`CONTINUOUS'` (the default) or '`DISCRETE`'
`test_type`	The type of test to use: '`CHI_SQUARED'`, '`KOLMOGOROV_SMIRNOV'` or '`ANDERSON_DARLING'`.
`paramA`	Parameter A estimated from the sample (the location parameter).
`paramB`	Parameter B estimated from the sample (the scale parameter).
`sig`	The goodness of fit value, based on test type. A small value indicates a significant difference between the sample and the uniform distribution. A number close to 1 indicates a close match.

176.1.6 WEIBULL_DIST_FIT Procedure

This procedure tests how well a sample of values fits a Weibull distribution.

Syntax

DBMS_STAT_FUNCS.WEIBULL_DIST_FIT (
   ownername    IN    VARCHAR2,
   tablename    IN    VARCHAR2,
   columnname   IN    VARCHAR2,
   test_type    IN    VARCHAR2 DEFAULT 'KOLMOGOROV_SMIRNOV',
   alpha        IN    NUMBER,
   mu           IN    NUMBER,
   beta         IN    NUMBER,
   sig          OUT   NUMBER);

Parameters

Table 176-7 WEIBULL_DIST_FIT Procedure Parameters

Parameter	Description
`ownername`	The schema where the table resides.
`tablename`	The table where the column resides.
`columnname`	The column of the table against which to run the test.
`test_type`	The type of test to use: '`CHI_SQUARED'`, '`KOLMOGOROV_SMIRNOV'` or '`ANDERSON_DARLING'`.
`alpha`	The scale parameter.
`mu`	The location parameter.
`beta`	The slope/shape parameter.
`sig`	The goodness of fit value, based on test type. A small value indicates a significant difference between the sample and the Weibull distribution. A number close to 1 indicates a close match.