15.00 - Case Study 1 - Teradata Database

Teradata Database Design

prodname
Teradata Database
vrm_release
15.00
category
User Guide
featnum
B035-1094-015K

Case Study 1

The following table indicates the number of distinct occurrences of City column values.

 

City Value

Frequency of Value

Log Frequency of Value

New York

                 4,000

                          3.602

Los Angeles

                      80

                          1.903

Chicago

                      35

                          1.544

Denver

                      30

                          1.477

Paris

                      30

                          1.477

London

                      30

                          1.477

Tokyo

                      25

                          1.398

Rio de Janeiro

                      20

                          1.301

The following histogram graphs the logarithm of the number of rows as a function of row values:

The maximum value for this set is 4,000, but what is the typical value?

It is easy to see by visual inspection of the table under “Case Study 1” on page 160 that the typical value for a variable is about 30. Note that the average value for this variable is 531.25, which is by no means typical of the values for the variable.

 

Maximum Value

Typical Value

4,000

30