The
              statistics for testing for monotonic trend
       
     
    
      
        To test for monotonic
            trend, the following five statistics are implemented in the package:
        
          
        1. The likelihood ratio
            test (Barlow et al. 1972, and Robertson et al. 1988)
        2. Williams (Williams,
            1971 and 1972)
        3. Marcus (Marcus, 1976)
        4. The M statistic (Hu et
            al., 2005) 
        5. The modified M
            statistic (Lin et al., 2007)
        
          
        The formulas for the
            statistics are presented below: