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

• 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