165 DBMS_STAT_FUNCS

The DBMS_STAT_FUNCS package provides statistical functions.

This chapter contains the following topic:

165.1 Summary of DBMS_STAT_FUNCS Subprograms

This table lists and briefly describes the DBMS_STAT_FUNCS subprograms.

Table 165-1 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

165.1.1 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 165-2 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.

165.1.2 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 165-3 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.

165.1.3 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 165-4 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.

165.1.4 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 165-5 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);

165.1.5 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 165-6 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.

165.1.6 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 165-7 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.