COMM 2002 Lecture 5: February 25th
2 Nov 2015
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Document Summary
What is the direction of the relationship (+ or -) Measures which tell us whether knowing the value of one variable reduces. Logic = proportional reduction of error (pre) chance of making an error in predicting the value of the other. Correlation value which varies between -1 and +1. The measures use the ordering of the categories in making their calculations each other. They are based on a comparison of all pairs of cases. Pairs are either concordant (exhibiting similar patterns) (c), discordant (as one value goes up on one variable, the value on the second variable goes up. But on the second case, it goes down) (d) or ties (t) Basic formula: n(c) n(d) divided by n(c) + n(d) If more pairs are concordant than discordant the measure will be posititve. If more pairs are discordant than concordant the measure will be negative. If the discordant pairs = the concordant pairs, the measure will be equal 0.
