A recent article in an agricultural research journal reports

A recent article in an agricultural research journal reports a correlation of +.7 between crop yield and total rainfall for a large sample of fields. It also reports a correlation of of -.8 between crop yield and average high tempurature for the same group of fields. Only fields with measurements on all three variables were included in the study. Which of the following interpretations is the most correct?

The correlation of -.8 indicates a stronger a relationship than the correlation of +.7.

The correlation of -.8 indicates a weaker a relationship than the correlation of +.7.

It is impossible to tell which correlation is stronger.

The correlation of +.7 is just as strong as the correlation of -.8.

Solution

Correlation coefficient can take value between -1 and +1. -1 shows the perfect negative linear relationship and +1 shows the perfect positive linear relationship between the variables. As the correlation coefficient comes close to 0, relationship between the variables become weaker. So 0.8 shows stronger negative linear relationship is comaprison to +7 which shows positive linear relationship between the variables. So option A is correct.