gcat.test {gCat}

Graph-based two-sample tests for categorical data

Description

This function performs the two-sample tests for categorical data utilizing similarity information among the categories. You can either provide a distance matrix on the categories (through the "distmatrix" argument) or a similarity graph on the categories directly (through the "C0" argument) or both. The outputs of this function are the test statistic(s) and p-value(s).

Usage

gcat.test(counts, distmatrix=NULL, C0=NULL, method="C-uMST", Nperm=0)

Arguments

counts

It is a K by 2 matrix, where K is the number of categories. It specifies the counts in the K categories for the two samples.

distmatrix

A K by K matrix, which is the distance matrix on the categories. This needs to be specified if you include any of the four methods – "aMST", "uMST", "C-uMST" and "C-uNNB" – in the "method" argument.

C0

A similarity graph on the categories. It is a E by 2 matrix, where E is the number of edges in the graph. Each row in C0 corresponds to an edge in the graph, and the two numbers are the category indices connected by the edge. This needs to be specified if you include "RC0" or "TC0" in the "method" argument.

method

This argument specifies the test statistic(s) to be computed. It can be any combination of {"aMST", "C-uMST", "uMST", "C-uNNB", "RC0", "TC0"}. If you choose more than one method, use c(,) to combine them. For example: c("C-uMST", "uMST", "RC0"). The details of the statistics can be found in the paper: Chen, H. and Zhang, N.R. (2013) Graph-based tests for two-sample comparisons of categorical data. Statistica Sinica, 23, 1479-1503.

Nperm

Number of permutations in calculating the permutation p-value. This needs to be specified if the method is "aMST". For other methods, specifying this argument would provide in the result the permutation p-value in addition to the approximate p-value, which is calculated through asymptotic theories.

Examples

data(Example)
gcat.test(mycounts,mydist,myedge,method=c("aMST","C-uMST","uMST","C-uNNB","RC0","TC0"),Nperm=1000)
gcat.test(mycounts,mydist,method=c("C-uMST","uMST"))
gcat.test(mycounts,mydist)
gcat.test(mycounts,myedge,method="RC0")