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Which Test is Used to Verify Assumptions in TTest

• To: mathgroup at smc.vnet.net
• Subject: [mg120132] Which Test is Used to Verify Assumptions in TTest
• From: Gregory Lypny <gregory.lypny at videotron.ca>
• Date: Sat, 9 Jul 2011 07:32:37 -0400 (EDT)

Hello everyone,

	I've run some simple t-tests of means using TTest and was pleased to see that Mathematica pretests for the validity of underlying assumptions.  In a very skewed sample, I received a warning that the normality assumption had likely been violated.  The warning looked like this:

	TTest::nortst: "At least one of the p-values in 0., resulting from a test for normality, is below 0.05. The tests in T require that the data is normally distributed.

	Is it possible to find out precisely which pretest Mathematica performed in order to generate that message?

Regards,

Gregory

• Follow-Ups:
  • Re: Which Test is Used to Verify Assumptions in TTest
    • From: Andy Ross <andyr@wolfram.com>
  • Re: Which Test is Used to Verify Assumptions in TTest
    • From: "Hobbs, Sylvia (DPH)" <sylvia.hobbs@state.ma.us>