Apizza delivery driver, always trying to increase tips, runs an experiment on his next 40 deliveries. he flips a coin to decide whether or not to call a customer from his mobile phone when he is five minutes away, hoping this slight bump in customer service will lead to a slight bump in tips. after 40 deliveries, he will compare the average tip percentage between the customers he called and those he did not. what are the experimental units and how did he randomize treatments?

The experimental units are the customers.

The treatments were randomized through a coin flip.

Explanation:

In experimental design, experimental units refers to those objects or subjects upon which the experiment is performed. The procedure performed on the experimental units is known as treatment. In this example, the experimental units are the customers, and the treatment is the phone call. The pizza delivery driver randomizes the application of treatments when he flips a coin to decide whether or not to call customers before deliveries are made. So to summarize, he expects the treatment (phone call) randomly (through a coin flip) performed on the experimental unit (customers) will result in an increase in tips.

answer; all of the answers are correct;