University:
Missouri State University
Course:
MTH 340 | Statistical Methods
Academic year:

2022
Views:

411

Pages:

2
Author:

Adelyn Pacheco

Stat and Data Analysis 4.2 More LSRL 1. Open the group USEDCAR to get the lists USEDA and USEDB. USEDA is the age of the used Corolla. USEDB is the price listed in the local paper for the car. a) Create the scatterplot. Describe the association. Negative Linear Strong(r = -0.945) No outliers b) Write the LSRL. y = -924x + 12319.59 c) What is the correlation? What does it tell you? r = -0.945; Strong, negative linear association d) What is the slope? Interpret in the context of the problem. Slope = -924; For every increase of 1 year in the age of the car there tends to be a decrease of 924 dollars in the selling price. e) If you want to sell a 7-year-old Corolla, what price seems appropriate? y = -924(7) + 12319.59 y = $5851.59 f) What is the residual for both cars that were 3 years old? y = -924(3) + 12319.59 y = $9547.59 e = 10995 – 9547.59 e = $1447.41 g) You have the chance to buy one of two cars. They are about the same age and appear to be in equally good condition. Would you rather buy the one with a positive residual or a negative residual? You want the one with the negative residual because the actual price is less than you would expect. So it’s cheaper. h) Would this regression model be useful in establishing a fair price for a 20-yearold car? No. 20 years is too far out of the range of the data. i) What is R2? What does this mean in the context of the problem? R2 = 89.4% 89.4% of the variability in selling price can be explained by variations in the age of the car. j) What percent of the variability in price is not being explained by the linear model? 10.6% of the variability in selling price is due to other factors. k) What other factors may be contributing to the change in price? Condition of the car. Model Etc. l) Create and sketch the residual plot m) Does the linear model seem an appropriate one? There is no obvious curve in the residual plot so the linear model is appropriate.