What is the difference between discordant and concordant pairs? Which measure of association is concerned with pairing cases?

What will be an ideal response?

(i) a discordant pair is a pair of two cases that support a negative relationship; these pairs are found down and to the left on a contingency table. A concordant pair is two cases that support a positive relationship. These pairs are found down and to the right on a contingency table (ii) gamma