An observational study found that the amount of time a child spends learning an instrument is associated with standardized testing performance. The correlation coefficient was found to be r = 0.92. A conclusion was made that the more time a child spends learning an instrument, the better the child performs on standardized tests. Why is such a conclusion not correct? a
Causation cannot be determined from an observational study.

b
The sample was not representative of the population.

c
The correlation value should be negative for such a conclusion.

d
The correlation value should equal 0 for such a conclusion.

e
The correlation value implies that less than 85% of the variability in standardized testing performance can be explained by learning an instrument.