Scientists plotted data for two animal populations on a scatterplot: population A, which they graphed along the x-axis, and population B, which they graphed along the y-axis. The data showed a strong negative correlation. Which of the following statements is justified ?

Options

A. The rise in population A caused the decline in population B.
B. The decline in population B caused the rise in population A.
C. Because the correlation is negative, there cannot be causation between the two populations.
D. The rise in populatin A is correlated to the decline in population B, but causation is unknown.

Answer

D

Explanation

The fact that the two variables are strongly correlated, whether it be negatively or positively, shows only that there is a relationship between the variables. It does not indicate whether the change in one variable caused the change in the other. For example, p[opulation A might thrive in wet climates, while population B does not, and in the years studied, rainfall may have increased, which caused the changes in the populations. Eliminate (A) and (B). Conversely, the negative correlation does not discount the possibility of causation, rather, the data does not allow you to draw a conclusion about causation, so eliminate (C ). This means (D) is the correct answer.