Tuesday, January 5, 2010

Criteria for Selecting the Appropriate Test Statistic

























When sampling from a:Test statisticTest statistic
Small Sample
(n<30)
Large Sample
(n>30)
Normal distribution with known variancez-statisticz-statistic
Normal distribution with unknown variancet-statistict-statistic*
Nonnormal distribution with known variancenot availablez-statisitc
Nonnormal distribution with unknown variancenot availablet-statistic*

*The z-statistic is theoretically acceptable here, but use of the t-statistic is more conservative.

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