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Sleepy After Lunch

APSTAT-A0DGLE

Many office workers experience sleepiness after lunch that slows down their productivity. A psychologist runs a completely randomized experiment in an attempt to identify the causes of this sleepiness. 144 office workers are randomly assigned to one of the following groups:

Group A is assigned to a low-calorie lunch and a brightly-lit office.
Group B is assigned to a low-calorie lunch and a softly-lit office.
Group C is assigned to a high-calorie lunch and a brightly-lit office.
Group D is assigned to a high-calorie lunch and a softly-lit office.

An hour after lunch, all the workers are asked to rate their sleepiness on a scale from 1 to 10.

Which of the following statements is false?

A

There are four explanatory variables.

B

The response variable is the level of sleepiness reported by the workers after lunch.

C

The experimental units are the 144 office workers.

D

The type of lunch and the type of office lighting are the explanatory variables.

E

There are two levels of lunch type and two levels of office lighting.