Question

Question 1:

Consider a case where we do a simple linear regression of the relationship between daily coffee intake (predictor, a quantitative variable expressed in number of 8oz cups per day) and sleep quantity (outcome, a quantitative variable measured in hours slept per night). What kind of measure of effects does a simple regression give us?

1. Unadjusted effect of daily coffee intake on sleep quantity, measured in the amount of change in hours slept per night we expect for every unit increase in cups of coffee consumed per day
2. Adjusted effect of daily coffee intake on sleep quantity, measured in the amount of change in hours slept per night we expect for every unit increase in cups of coffee consumed per day
3. Unadjusted effect of daily coffee intake on sleep quantity, measured in the odds of having a low number of hours slept per night for high coffee intake subjects compared to low coffee intake subjects
4. Adjusted effect of daily coffee intake on sleep quantity, measured in the odds of having low hours slept per night for high coffee intake subjects compared to low coffee intake subjects

Answer 1

The answer is "Unadjusted effect of Daily Coffee intake on sleep quantity, measured in amounts of change in hours sleep per night we expect for every unit increase in cups of coffee consumed per day " , which appears as option 1.

By UNADJUSTED it means a simple relation between two variates where one effects the other without the presence of any other covariate.

The Regression predicts the number of hours of sleep that would be expected for a particular coffee consumption value. And one would expect it to be a negative relation. That is, lesser sleep for more coffee.