Sum of the Cross-Products for the DOLL-ECOL data

SS_XY = (1300-603.64)(20-20.55) +
      (1100-603.64)(46-20.55) +
      (1100-603.64)(35-20.55) +
      ( 510-603.64)(25-20.55) +
      ( 500-603.64)(15-20.55) +
      ( 490-603.64)(24-20.55) +
      ( 480-603.64)(18-20.55) +
      ( 380-603.64)(17-20.55) +
      ( 300-603.64)(11-20.55) +
      ( 250-603.64)( 9-20.55) +
      ( 230-603.64)( 6-20.55)

    =   -383 +          
       12632 +
        7172 +
        -417 +
         575 +
        -392 +
         315 +
         794 +
        2900 +
        4085 +
        5436 

     = 32717