lm(Y ~ X + ID) The first few rows of the coefficients table are below. Variable Estimate of coefficient P-value (intercept) 20 Less than 0.0001 X 3 Less than 0.0001 ID2 -4 Less than 0.0001 ID3 2 Less than 0.0001 ID4 0.02 0.85 When we control for individual variability, whenever X increases 6 units, the predicted value of Y increases ____ units