Correlated Samples Formulas
__
 X
__
 Y
S 
__
 D
 ŒD2 Ð (ŒD)2
S2 =   SS    
          NÐ1
SD  =    SS    
              NÐ1
           -
t  =                    
  =                N D = X Ð Y
N Ð 1 N = # of pairs
__
 D
S 
S D      this is the SE of difference between correlated means
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 D