A clinical psychologist obtained a large sample of adults. Each adult kept track of all the food and beverages he or she consumed for a week. From this, the psychologist calculated the average grams of caffeine consumed per day. The psychologist believed that caffeine, a stimulant, might be used to self-medicate for symptoms of ADHD. So, she also had all participants complete an ADHD symptom inventory. She wanted to see if people with more ADHD symptoms consumed more caffeine.

Determine if the study is descriptive, experimental, quasi-experimental, or correlational.