Why is Kendall's Tau always so high?

#1
Hi there, I'm using Kendall's Tau to check whether two judges agree on the ranking of some individuals.
According to what I have read on the internet*, W>0.5 means that there is at least a moderate agreement between the two judges.
The problem is that W is always super high for no reason. W=5 even if I say that the second judge gave 0 points to each individual:
0.26 0
0.16 0
0.36 0
0.38 0
0.34 0
... ....
Does anyone have any idea of what the problem might be?
Cheers!
 

Attachments

staassis

Active Member
#2
I do not quite understand the data you have shown. The data you have attached have only one variable, not two. What is W? Kendall's tau must take values in [-1,1].

In fact, the absolute value of Kendall's tau tends to be lower than that of Spearman's rho or Pearson's correlation. It is hard to achieve values close to -1 and +1. I have seen it on many data sets.
 

katxt

Active Member
#3
The problem is that W is always super high for no reason. W=5 even if I say that the second judge gave 0 points to each individual:
W is Kendall’s coefficient of concordance which is different from Kendall's tau.
In either case, if you are doing this by hand, I would check that you understand the formula and that you are actually calculating tau because the answer cannot ever be 5.