Question

Which of these r-values represents the strongest correlation? A.-0.8 B.-0.7 C.-0.9 D.-0.6

Answer 1

It would be c. A perfect correlation will be either a 1 or a -1. The answer that is closest to one of these is c, -0.9.

Answer 2

-0.9 represents the strongest correlation

Solution-

Correlation coefficient-

1. Correlation coefficient measuring a linear relationship between the two variables indicates the amount of variation of one variable accounted for by the other variable.
2. The coefficient of correlation always lies between –1 and 1, including both the limiting values, i.e.
   `-1\leq r\leq 1`

The more closer its absolute value to 1, the stronger the relationship is.

If r is -ve, then the relationship is negative (i.e if one increases then the other must decrease)

If r is +ve, then the relationship is positive (i.e if one increases then the other must increase)

As, in case of -0.9, its absolute value 0.9 is more closer to 1, so it is the strongest correlation (strong-negative correlation)