There are ten shirts in your closet, five blue and five green. Three of the blue shirts and three of the green shirts fit well. The others are too big. You randomly select a shirt to wear. It is blue or fits well.

An energy drink company claims that its product increases students' memory levels. to support its claims, the company issues advertisements claiming that 8 out of 10 people (chosen randomly from across the country) who tried their product reported improved memory. the missing component in this study is a .