HP 39g+ Graphing manual Two-Sample T-Test, Pooled?

Two-Sample T-Test

Menu name	T-Test: ∝1 – ∝2
	The Two-sample T-Test is used when the population
	standard deviation is not known. On the basis of statistics
	from two samples, each sample from a different
	population, this test measures the strength of the evidence
	for a selected hypothesis against the null hypothesis. The
	null hypothesis is that the two populations means are
	equal H 0: ∝1 = ∝2.
	You select one of the following alternative hypotheses
	against which to test the null hypothesis
			H1:∝1 < ∝2
			H1:∝1 > ∝2
			H1:∝1 ≠ ∝2
Inputs	The inputs are:
	Field		Definition
	name
			Sample 1 mean.
		x1
			Sample 2 mean.
		x2
	S1		Sample 1 standard deviation.
	S2		Sample 2 standard deviation.
	n1		Sample 1 size.
	n2		Sample 2 size.
	α		Significance level.
	_Pooled?		Check this option to pool samples
			based on their standard deviations.

9-14 Inference aplet