Documentation

tiedrank

Rank adjusted for ties

Description

[R,TIEADJ] = tiedrank(X) computes the ranks of the values in the vector X. If any X values are tied, tiedrank computes their average rank. The return value TIEADJ is an adjustment for ties required by the nonparametric tests signrank and ranksum, and for the computation of Spearman's rank correlation.

[R,TIEADJ] = tiedrank(X,1) computes the ranks of the values in the vector X. TIEADJ is a vector of three adjustments for ties required in the computation of Kendall's tau. tiedrank(X,0) is the same as tiedrank(X).

[R,TIEADJ] = tiedrank(X,0,1) computes the ranks from each end, so that the smallest and largest values get rank 1, the next smallest and largest get rank 2, etc. These ranks are used in the Ansari-Bradley test.

Examples

Counting from smallest to largest, the two 20 values are 2nd and 3rd, so they both get rank 2.5 (average of 2 and 3):

tiedrank([10 20 30 40 20])
ans =
1.0000    2.5000    4.0000    5.0000    2.5000

Algorithms

tiedrank treats NaNs in X as missing values and ignores them. The rank of NaNs in the output argument R is NaN.