New Statistics Release
May
2
Written by:
Charles Flock
5/2/2010 4:12 PM
XLeratorDB/statistics version 1.05 contains eight new chi-squared functions that give you the flexibility to enter the expected results.
We have released a new version of the XLeratorDB/statistics package. The changes all had to do with calculation of the chi-squared statistic and the chi-squared test. No existing functions were changed, but we added eight new functions:
· CHISQ2—calculates the chi-squared statistic on a de-normalized table
· CHISQ2_q—calculates the chi-squared statistic on a de-normalized resultant table
· CHISQN2—calculates the chi-squared statistic on a normalized table
· CHISQN2_q—calculates the chi-squared statistic on a normalized resultant table
· CHITEST2—calculates the chi-squared test on a de-normalized table
· CHITEST2_q—calculates the chi-squared test on a de-normalized resultant table
· CHITESTN2—calculates the chi-squared test on a normalized table
· CHITESTN2_q—calculates the chi-squared test on a normalized resultant table
These functions require expected results as input into the function rather than automatically calculating the expected results. They work just like the existing functions (which do not have a ‘2’ in the function name) which do not accept expected results and calculate them internally. It is possible, for example, for CHISQ and CHISQ2 to return different answers depending upon the expected results supplied to the CHISQ2 function. CHISQ calculates the expected results in without any internal rounding. If the expected results supplied to the CHISQ2 function are rounded (or wrong), then the results will differ.
So, this SELECT statement :
SELECT wct.CHISQ_q(
'SELECT 28,35,54 UNION ALL
SELECT 60,43,35 UNION ALL
SELECT 52,48,28')
Produces a result of 22.451703426585
Whereas this SELECT statement:
SELECT wct.CHISQ2_q(
'SELECT 28,35,54 UNION ALL
SELECT 60,43,35 UNION ALL
SELECT 52,48,28'
,'SELECT 42.77,38.49,35.74 UNION ALL
SELECT 50.44,45.4,42.16 UNION ALL
SELECT 46.79,42.11,39.1')
Produces a result of 22.4562079299414
For more information about these functions, please see the XLeratorDB/statistics documentation.