Based on the following graph which of the following is a rea

Based on the following graph, which of the following is a reasonable estimate for r, the correlation coefficient?

-.75

-.20

-.01

.15

.82

Solution

Correlation can tell you something about the relationship between variables. It is used to understand:

Statistical correlation is measured by what is called coefficient of correlation (r). Its numerical value ranges from +1.0 to -1.0. It gives us an indication of the strength of relationship.

In general, r > 0 indicates positive relationship, r < 0 indicates negative relationship while r = 0 indicates no relationship (or that the variables are independent and not related). Here r = +1.0 describes a perfect positive correlation and r = -1.0 describes a perfect negative correlation.

Closer the coefficients are to +1.0 and -1.0, greater is the strength of the relationship between the variables.

As a rule of thumb, the following guidelines on strength of relationship are often useful (though many experts would somewhat disagree on the choice of boundaries).

The most used correlation coefficients only measure linear relationship. the above scatter plot shoes an strong non linear relationship between the variables, r is close to 0 or even 0 that is scatter diagram can roughly indicate the existence or otherwise of a non linear relationship.. then the pointsa are moved from left to right hence it shows an positive relationship . hence the value of r is roughly 0.15. the answer is D)