Dr. Smith is interested in the relationship between nicotine and hand steadiness. Two groups participated in the experiment. One group smoked 5 cigarettes in an hour, while another group read during the same hour. Participants are then tested on the hand steadiness apparatus (yielding a score with the number of errors made). What is the independent variable

Exposure to nicotine is the independent variable

Step-by-step explanation:

An independent variable is a factor that remains unchanged (by other factors in the experiment) throughout the course of an experiment. It can however be manipulated by the researcher. A dependent variable, on the other hand, is the factor being measured that relies on the independent variable. In the case above, exposure to 1 hr of nicotine intake forms the independent variable while the levels of hand steadiness, which will be measured, form the dependent variable.