Oracle® Database SQL Reference 10g Release 1 (10.1) Part Number B1075901 


View PDF 
STATS_BINOMIAL_TEST
is an exact probability test used for dichotomous variables, where only two possible values exist. It tests the difference between a sample proportion and a given proportion. The sample size in such tests is usually small.
This function takes four arguments: expr1
is the sample being examined. expr2
contains the values for which the proportion is expected to be, and p
is a proportion to test against. The fourth argument is a return value of type VARCHAR2
. If you omit the fourth argument, the default is TWO_SIDED_PROB
. The meaning of the return values is shown in Table 73.
Table 73 STATS_BINOMIAL Return Values
Return Value  Meaning 

TWO_SIDED_PROB 
The probability that the given population proportion, p , could result in the observed proportion or a more extreme one. 
EXACT_PROB 
The probability that the given population proportion, p , could result in exactly the observed proportion. 
ONE_SIDED_PROB_OR_MORE 
The probability that the given population proportion, p , could result in the observed proportion or a larger one. 
ONE_SIDED_PROB_OR_LESS 
The probability that the given population proportion, p , could result in the observed proportion or a smaller one. 
EXACT_PROB
gives the probability of getting exactly proportion p. In cases where you want to test whether the proportion found in the sample is significantly different from a 5050 split, p
would normally be 0.50. If you want to test only whether the proportion is different, then use the return value TWO_SIDED_PROB
. If your test is whether the proportion is more than the value of expr2
, then use the return value ONE_SIDED_PROB_OR_MORE
. If the test is to determine whether the proportion of expr2
is less, then use the return value ONE_SIDED_PROB_OR_LESS
.
The following example determines the probability that reality exactly matches the number of men observed under the assumption that 69% of the population is composed of men:
SELECT AVG(DECODE(cust_gender, 'M', 1, 0)) real_proportion, STATS_BINOMIAL_TEST (cust_gender, 'M', 0.68, 'EXACT_PROB') exact, STATS_BINOMIAL_TEST (cust_gender, 'M', 0.68, 'ONE_SIDED_PROB_OR_LESS') prob_or_less FROM sh.customers;