A manager at a large company wants to understand whether the employees are feeling overworked while completing a project. The company has 200 employees working on the project all over the world, but the manager only has time and money to collect information from 50 people.

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 .