If X is a normal random variable with mean 40 and standard deviation 10 and P(X < 38) = 0.4207, then P(X ≤ 38) = _________ .
Step 1 of 5) A normal random variable with mean 40 and standard deviation 10 and P(X < 38) = 0.4207, then P(X ≤ 38). The regression coefficient, b1 = 1.014, means that, if the patient’s age increases by one year then total cholesterol increases by 1.014 mg/dL, on average, assuming that the average daily consumption of saturated fat remains unchanged. The regression coefficient, b2 = 3.244, means that, if the patient’s average daily consumption of saturated fat increases by 1 gram, total cholesterol increases by 3.244 mg/dL, on average, assuming that age remains unchanged. Interaction Effects In Example 3, we were able to interpret the regression coefficients by holding the value of one explanatory variable fixed and determining how a 1-unit change in the other explanatory variable affects the response variable. We were able to do this because the explanatory variables had an additive effect, or did not interact. One hint that the explanatory variables do not interact comes from the low correlation between them. A positive correlation between two explanatory variables, x1 and x2, implies that, if x1 changes then x2 is likely to change.