The blank in the question is most likely referring to a "relationship" or "correlation."

The full sentence would be:

"A correlation exists between two variables when the values of one variable are somehow associated with the values of the other variable."

Would you like further details on this, or do you have any other questions?

Here are 5 related questions to deepen your understanding:

1. What is the difference between positive and negative correlation?
2. How is correlation measured statistically?
3. What are examples of correlation in real-world data?
4. What is the difference between correlation and causation?
5. How can outliers affect correlation?

Tip: Remember, correlation does not imply causation; two variables can be related without one directly causing the other.