Questions

Posted: August 27th, 2021

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Week 6

Question 1

The plot shows a trend such that miles per gallon (MPG) and Horsepower are negatively associated, that is, an increase in the horsepower leads to a decrease in MPG. As horsepower increases, the speed of the car increases and the car adopts an increasing acceleration but there is high fuel burning. Therefore, the MPG is expected to be lower compared to cars with low horsepower.

Question 2

The coefficients of correlation between MPG and horsepower is -0.759395 while that between MPG and weight of the car is -0.857727. The coefficients of correlations are negatively correlated with MPG and horsepower having a strong correlation (- 0.76) than MPG and the weight of the car (- 0.86). Coefficients of correlation indicate a strong, weak, or no correlation. Thus, the strongest correlation is shown by the direction of the coefficient. In the case of no correlation, the coefficient is zero.

Question 3

The multiple regression for predicting miles per gallon as response variable implies that the miles per gallon are a dependent variable. The weight and horsepower are predictors or independent variables. Therefore, the regression equation from the output is as follows;

From the model, holding all other factors constant, the consumed miles per gallon is 37.0692 units. However, a unit change in weight reduces this consumption by 3.8805 units, and a unit change in horsepower decreases miles per gallon by about 0.0314 units. The assessment of the model reveals that the two factors explains about 81.5% change in miles per gallon. Also, the p-value as estimated reveals that p-value >t implying that the model is significant. Thus, 18.5% is explained by factors outside the model.