Mantel-Haenszel statistical test

Here you can still use the Pearson chi-square test as shown in the 2x2 table example as long as your response variable is nominal and merely descriptive. If your response variable is ordinal, meaning that it is an ordered sequence, and you can use a parametric test, then you should use the Mantel-Haenszel test statistic for parametric tests of association. For instance, if in our previous example the variable called headache was coded as a 2 when the patient experienced extreme headache, a 1 if mild headache, and a 0 if no headache, then headache would be an ordinal variable. You can get the Mantel-Haenszel /pvalue by running the following SAS code ... 

As we shall see later the data type to a large extent determines the class of statistical tests that we undertake. Commonly for continuous data we use the t-tests and their extensions analysis of variance and analysis of covariance. For binary, categorical and ordinal data we use the class of chi-square tests (Pearson chi-square for categorical data and the Mantel-Haenszel chi-square for ordinal data) and their extension, logistic regression. 

Mantel-Haenszel test, the combined studies indicated a highly significant difference (c - 483 df = 1 p < 10 This finding represents overwhelming statistical evidence that in schizophrenia, antipsychotics prevent relapse. 

The analytical approach to safety data is limited but growing (Dubey et al., 2006). Some suitable statistical techniques that can be employed include Fisher s exact test, the Mantel-Haenszel test, and the adapted Cochran-Mantel-Haenszel test, all of which can be used to compare adverse event rates between treatment groups (see Chow and Liu, 2004, for further details). 

Patency of the prostheses were determined by re-exposure and direct inspection. The prostheses (series III) in which the elastic index best matched the dog femoral arteries (approx. 7.4 dynes/mm) had the best patency rate at one month. When the prostheses were either more elastic or less elastic, the patency dropped significantly. The decrease in the number patent at one month was statistically significant for those grafts less elastic than the arteries (values significant at <0.005 by the Goehran-Mantel-Haenszel Test) in those prostheses which were more elastic, the low number of samples reduced the significance of the data. However, the trend was toward decreased patency. 

The formula for the test statistic is somewhat complex, but again this statistic provides the combined evidence in favour of treatment differences. When Mantel and Haenszel developed this procedure they calculated that when the treatments are identical the probabilities associated with its values follow a x i distribution. This is irrespective of the number of outcome categories, and the test is sometimes referred to as the chi-square one degree of freedom test for trend. 

One method applicable to the difference of two proportions, originally described by Mantel and Haenszel (1959) and well described by Fleiss et al. (2003), utilizes weights that are proportional to the size of each stratum (in this case, centers) to calculate a test statistic that follows approximately a distribution. 

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