.-
help for ^mv2snp^                             (STB-42: snp14)
.-

Two-sample multi-variate nonparametric test (Leach, 1991)
---------------------------------------------------------

	^mv2snp^ varlist, ^by(^groupvar^)^ [^verb^ose]


Description
-----------

^mv2snp^ performs a two-sample multi-variate nonparametric test given by 
Leach (1991). The test-statistic (U*) is asymptotically distributed as chi-
squared(p) where p is the number of variables. Significant values of U* 
indicate a difference between the two groups.


Options
-------

^by^(groupvar) is not optional; it specifies the variable identifying the groups.

^verbose^ is optional.  If included, additional output is provided.


Example
-------

Data are entered into Stata with a grouping variable. For example, in the two-
variable case;

   . ^list ghq ies group^

         ghq       ies      group  
 1.       32        38          h  
 2.       34        17          h  
 ..       ..        ..          .
 ..       ..        ..          .
22.       22         7          s  
23.       11         5          s  

   . ^mv2snp ghq ies, by(group) verbose^


Remarks
-------

The grouping variable may be alpha or numeric and need not be named `group'.
The data do not need to be sorted before applying ^mv2snp^.  When @egen!rank@ing
the data, ^mv2snp^ does not exclude data values of zero.  ^mv2snp^ does, however,
perform case-wise deletion for subjects with missing data.


Saved Results
-------------

^mv2snp^ saves the following results:

        S_1     U*
        S_2     Combined sample size
        S_3     Size of smaller sample
        S_4     Number of variables


Reference
---------

Leach, C. 1991.  Nonparametric Methods for Complex Data Sets, in New 
Developments in Statistics for Psychology and the Social Sciences 
(Vol. 2), ed. P. Lovie and A. D. Lovie. British Psychological Society 
and Routledge.


Author
------

      Andy Perkins
      University of East Anglia, UK
      email: a.perkins@@uea.ac.uk


Also see
--------

    STB:  STB-42 snp14