wanova

Performs Welch's alternative to one-way analysis of variance (ANOVA).

% Function File: [p, F, df1, df2] = wanova (y, g)

%

% Perform a Welch's alternative to one-way analysis of variance

% (ANOVA). The goal is to test whether the population means of data

% taken from k different groups are all equal. This test does not

% require the condition of homogeneity of variances be satisfied.

% For post-tests, it is recommended to run the function 'multicmp'.

%

% Data should be given in a single vector y with groups specified by

% a corresponding vector of group labels g (e.g., numbers from 1 to

% k). This is the general form which does not impose any restriction

% on the number of data in each group or the group labels.

%

% Under the null of constant means, the Welch's test statistic F

% follows an F distribution with df1 and df2 degrees of freedom.

%

% The p-value (1 minus the CDF of this distribution at F) is

% returned in the p output variable.

%

% Bibliography:

% [1] Welch (1951) On the Comparison of Several Mean Values: An

% Alternative Approach. Biometrika. 38(3/4):330-336

% [2] Tomarken and Serlin (1986) Comparison of ANOVA alternatives

% under variance heterogeneity and specific noncentrality

% structures. Psychological Bulletin. 99(1):90-99.