Ttest2u

Purpose

Two sample t-test (assuming unequal variance).

Synopsis

result = ttest2u(x,y,test,dfapp)

Description

Calculates a two sample t-test for samples (x) and (y) assuming unequal variance.

Inputs

• x = matrix (column vector) in which the sample data is stored.

• y = matrix (column vector) in which the sample data is stored.

• ttest = [-1,{0},1] indicates what ttest is for:

-1 - lower tail H0: mean(x) <= mean(y)

0 - wo-tail H0: mean(x) \~= mean(y) {default}

1 - upper tail H0: mean(x) >= mean(y)

• dfapp = [{-1}, 1] indicates which degree of freedom calculation to use.

-1 - indicates Welch's approximate degrees of freedom {default}

1 - indicates Satterthwaite's approximate degrees of freedom

Outputs

The output (result) a structure with the following fields:

• t = test statistic.

• p = probability value

• mean1 = mean of x

• mean2 = mean of y

• var1 = variance of x

• var2 = variance of y

• n1 = length of x

• n2 = length of y

• pse = pooled standard error

• df = degress of freedom

• app = 'Satterthwaite' or 'Welch'

• hyp = hypothesis being tested

Examples

result = ttest2u(x,y);

result = ttest2u(x,y,test);

result = ttest2e(x,y,test,dfapp);

See Also

ttest1, ttest2e, ttest2p