EASY
12th Tamil Nadu Board
IMPORTANT
Earn 100

Find the Karl Pearson’s coefficient of correlation for the following data.

 Wages 1001011021021009997989695 Cost of living 98999997959295949091

Important Points to Remember in Chapter -1 - Correlation Analysis from Tamil Nadu Board Statistics Standard 12 Solutions

1. Correlation and its types:

It is the study about finding the linear relationship between two variables

(i) Simple correlation:

(ii) Partial correlation

(iii) Multiple correlation.

2. Methods to find correlation:

(i) Scatter diagram

(ii) Karl Pearson's product moment correlation coefficient

(iii) Spearman's Rank correlation coefficient

(iv) Yule's coefficient of Association

3. Scatter diagram and types of correlation:

A scatter diagram is the simplest way of the diagrammatic representation of bivariate data.

(i) Positive correlation:

If the plotted points in the plane form a band and they show the rising trend from the lower left hand corner to the upper right hand corner.

(ii) Negative correlation:

If the plotted points in the plane form a band and they show the falling trend from the upper left hand corner to the lower right hand corner.

(iii) Uncorrelated:

If the plotted points spread over in the plane then the two variables are uncorrelated.

(iv) Perfect positive correlation:

If all the plotted points lie on a straight line from lower left hand corner to the upper right hand corner.

(v) Perfect negative correlation:

If all the plotted points lie on a straight line falling from upper left hand corner to lower right hand corner.

4. Karl Pearson's coefficient correlation:

rX,Y=ni=1nxiyi-i=1nxii=1nyini=1nxi2-i=1nxini=1nyi2-i=1nyi2

5. Spurious correlation:

It means an association extracted from correlation coefficient that may not exist in reality.

6. Spearman’s rank correlation coefficient:

ρ=1-6i=0*Di2nn2-1,Di=R1i-R2i

7. Spearman’s rank correlation coefficient for repeated ranks:

ρ=1-Di2+112m13-m1+112m23-m2+nn2-1

8. Yule's coefficient:

Q=(AB)(αB)-(Aβ)(αB)(AB)(αB)+(Aβ)(αB)