<p>The first question is: </p>
<p>Which of the following is a key distinction between well designed experiments and observational studies?</p>
<p>I've been searching on google and I can't seem to find what year this exam is or any of the answers to the mc. Can anyone show me where I can find the answers to the mc? Thanks.</p>
<p>That sounds like the type of question that would appear on the exam every year. Just to answer the question, since I need to review anyway: Treatments are imposed and variables are manipulated in experiments to look for a change that can be explained with a control. An observational study simply includes observation.</p>
<p>It’s from the 2002 ap test. :)</p>