The test used is the two sample
-test. The test statistic
is defined by;
where
is the pooled variance of the two samples.
The test of
is carried out against one of three possible alternatives:
-
(i); the significance level, , i.e., a two tailed probability.
-
(ii); the significance level, , i.e., an upper tail probability.
-
(iii); the significance level, , i.e., a lower tail probability.