Coefficient of correlation...ppt

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1. Coefficient of correlation

2. A statistic representing how closely two
variables co-vary; it can vary from -1
(perfect negative correlation) through 0
(no correlation) to +1 (perfect positive
correlation).

3. •The correlation coefficient, denoted by r, is a
measure of the strength of the straight-line or
linear relationship between two variables. The
correlation coefficient takes on values ranging
between +1 and -1.
•The quantity r, called the linear correlation
coefficient, measures the strength and the
direction of a linear relationship between two
variables

4. Type of correlation coefficient
1.Perfect Positive correlation
2.Perfect negative correlation
3.ModeratelyPositive correlation
4.Moderatenegative correlation
5.Absolute no correlation

5. Perfect Positive correlation
•If xand yhave a strong positive linear correlation,
ris close to +1.An rvalue of exactly +1
indicates a perfect positive fit.Positive values
indicate a relationship between xand yvariables
such that as values for xincreases, values fory
also increase.

7. Perfect negative correlation
•If xand yhave a strong negative linear
correlation, ris close to -1.An rvalue of exactly
-1 indicates a perfect negative fit.Negative
values indicate a relationship between xand y
such that as values for xincrease, values for y
decrease.

9. ModeratelyPositive correlation
•0<r<1
Moderate negative correlation
-1<r<1

13. Absolute no correlation
•If there is no linear correlation or a weak
linear correlation, ris close to 0.A value near
zero means that there is a random, nonlinear
relationship between the two variables

14. Methods of computing the
correlation
•karl pearson’s correlation coefficient
•spearman’s rank correlation coefficient

15. karl pearson’s correlation
coefficient

17. Spearman’s rank correlation
coefficient