k 1 Additional file 1 - Algorithm for computing v i 1 2 i Consider the case of i ties. Let l0 = 0 and C00 1 . Then under H0, vi2 1l1 .... li k k k k n*[ (nt 1) I (t l1 )I (t li ) ]{ [ t 1 m 1 n 1 k i m k i n 1 cuv ]} (2k i)! u m vn cuv [k t1 t 2 t3 t 4 I (m l1 ) I (m li )]! [k t1 t2 t3 t4 I (n l1 ) I (n li )]! (t1 t2 t3 t4 )! CtI1SSt(2u, vt3) tI4SL (u ,v ) I LS (u ,v ) I LL (u ,v ) m 1 I ( l1 m ) I ( l i m ) n 1 I ( l1 n ) I ( l i n ) k m I ( l1 m ) I ( l i m ) k n I ( l1 n ) I ( l i n ) w0 x 0 y 0 z 0 CwI SS (u ,v) t1 CmI SL1(uI,v(l)1t 2m) I (li m) w CxISS (u ,v )t1wCnILS1(uI ,(vl1)nt3)I (li n)x CyI LS (u ,v ) t3 [ n 1 I (l1 n) I (li n) x]CkI LLm(u,Iv()l1t 4m) I (li m) y k m I ( l1 m) I ( li m) y ] CzISL (u ,v )t2 [ m1I (l1m)I (li m)w] CkI LLn(uI,v(l)1tn4 )[ I (li n ) z 1 k2 Hence, we define ISS(u, v), ISL(u, v), ILS(u, v), and ILL(u, v) = The numbers of {1 : u-1}∩{1 : v-1}, {1 : u-1}∩{v+1 : 2k-i}, {u+1 : 2k-i}∩{1 : v-1}, and {u+1 : 2k-i}∩{v+1 : 2k-i}. t1, t2, t3, and t4 = the numbers of ties from ISS(u, v), ISL(u, v), ILS(u, v), and ILL(u, v). If b > a in C ba , vuv = 0. In displays (1) and (2), we present formulas for the mean and variance of test statistic under H0. The proof of V0(T) is not presented for the sake of brevity as the arguments are similar to those presented for the case of ‘‘exactly three ties’’ in the proof of Theorem 1. Moreover, we illustrate a direct calculation of E0(T) and V0(T) in the particular case of k 3, and ni 1, 2, or 3 in Table 1. Note that (n1 , n2 , n3 ) = (2, 1, 1 1), E0(T) = 2 and V0(T) = 2.667, which is in agreement with what we obtain using equation (1) and (2), namely, E0(T) = 2, and 1 3 2 v0 1 ni 1.333 , 3 i 1 3 1 v 2 i i 1 2 1 [ 1 1 1 1 1 0!0!2!(C22 C22 ) 2 0!1!1!(C12C11 C11C11 ) 2 0! 24 3 24 3 24 1!1!(C12C11 C11C11 ) 1 1 1 1 1!0!1!(C12C11 C11C11 ) 2 1!1!1!(C11C12C11 C11C12C11 ) 2 3 24 3 24 1 1 1 1 1 1 1!1!0!(C11C11 C12C11 ) 2 1!0!1!(C12C11 C11C11 ) 2 1!1!0!(C11 2 3 24 3 24 3 24 C11 C12C11 ) 31 v i 1 2 i 1 1 1 1!1!1!(C13C12C11 ) 2 ] , 2 3 24 3 2 1 [ 2 1 1 1 1 1 1 1 1 1 1 1 2 2 3 2 3 2 3 2 4 2 3 2 24 3 24 3 24 3 24 3 24 3 24 3 1 1 1 1 1 1 3 2 3 2 6 2 ] 0.667 , 24 3 24 3 24 3 1 1 vk2 2 6 ( ) 0.667 , 6 9 V0(T) = 1.333+0.667+0.667=2.667. 2