Prob&Stats - D1 - 1 quick answer needed - nothing in depth

I only need one answer of roughly 100 words or so. Nothing in depth is needed. Please, answer in your own words -no plagiarism from book or others.

(Please do not ask me to ask this question again on your page.)

Here is the question:

The Prob. and Stats. textbook asserts that it takes an experiment to establish cause and effect, and that observational research is insufficient to do so. Do you agree? Please explain.