Ttest2u

Purpose

Two sample t-test (assuming unequal variance).

Synopsis

result = ttest2u(x,y);

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

Description

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

Inputs

• x = matrix (or column vector) of data for the first sample.
• y = matrix (or column vector) of data for the second sample.

Optional Inputs

• ttest = [-1, {0} ,1] indicates what type of t-test to perform:

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

0: two-tail H0: mean(x) ~= mean(y) {default},

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

• dfapp = [ {-1} , 1] governs the algorithm for calculating degrees of freedom:

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

1: 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