dacohen/Rsquared

module Rsquared

       class PropTest < StatTest
                def initialize(data, p0, sided)
              @data = data
         @p0 = p0
         @sided = sided

         if (@data.length*@p0 < 10.0) or (@data.length*(1.0-@p0) < 10.0) then
            raise AssumptionError, "The number of successes or failures prediced by the proportion is too small"
         end
         
         @stderr = Math.sqrt((@p0*(1.0-@p0))/@data.length)
         @pstat = ((@data.sum.to_f/@data.length.to_f) - @p0)/@stderr
         @pvalue = Distribution::Normal::cdf(@pstat)
         self.setSidedness!(@sided)
        end


        ##
        # Returns the z-statistic
        
        def statistic
            @pstat
            end

        ## significant?, inspect implemented by inhertance
    end
end