Question

Identify the type of correlation coefficient apprpriate for measuring the relationship between X and Y :

1. X= sex (M or F); Y= income (dollars)

2. X= IQ (above of below 100); Y= GPA (above or below 60%)

Answer 1

Correlation coefficient is defined as the degree of linear relation between the variables,in other words,correlation is a statistical technique that can show whether and how strongly pairs of variables are related. Correlation coefficient (r) ranges from -1 to +1. The closer r is to +1 or -1, the more closely the two variables are related. If r is close to 0, it means there is no relationship between the variables. If r is positive, it means that as one variable gets larger the other gets larger. If r is negative it means that as one gets larger, the other gets smaller .

But sometimes though we get non zero value of correlation, but there exist no correlation logic wise between the variables.Such corelation is called sense less correlation.

1. X= sex and Y=income($)

Correlation coefficient is zero since there is no relationship between the sex of a person and his or her income. A male can earn more than female or a female can earn more than male. Or both can earn equal.

2.X=IQ and Y= GPA

There exist a positive value of correlation, since a student with good IQ will score better where as a student poor IQ might score bad .