Adding a participant variable to a design with an existing independent variable is one way to increase external validity. True or False

This schedule shows the opportunity cost of producing doughnuts, bagels, and croissants. refer to the schedule and use the drop-down menu to answer each question. on day 2, raj makes 70 more bagels than on day 1. what is the opportunity cost of producing 70 more bagels? on day 3, raj makes 50 more croissants than on day 2. what is the opportunity cost of producing fifty more croissants?

Where do most people in arabia and iraq live? a. in the fertile crescent b. in the rub, al-khali c. in cities d. in and around mecca

An individual who is experiencing a prolonged period of stress would likely have levels of circulating than an individual who was not experiencing stress.