Lin's concordance correlation coefficient (CCC) which is used to quantify the extent of agreement between two measures ranges between [-1,1]. I want to know under what condition does perfect discordance ($CCC=-1$) hold true? Based on my thinking and reasoning, I had few doubts which I would like to clarify:
Is this only possible when means of two variables equals 0, variances of two variables is identical and $PCC=-1$?
Is there any other possibility when $CCC=-1$ apart from 1.?