Problem Set 6 (1)

.pdf

School

University of Hawaii *

*We aren’t endorsed by this school

Course

310

Subject

Economics

Date

Jan 9, 2024

Type

pdf

Pages

8

Uploaded by LieutenantStarlingMaster218

Report
Problem Set 6 (With instructions) Individual or group. Use SWA_PS6_Soth west airlines file 1. Do a multiple regression using JetFuel ($/gal), DPI ($B), Recession and AirTran to predict Revenue for Southwest Airlines using data in the Data2 tab . Then use the results to predict Revenue on CEI tab 2012 with a 95% prediction interval estimate when JetFuel = 3.07, DPI = 10337, Recession = 0 and AirTran = 1. Write up a report of your analysis. You should include the following in your report: Interpretation of R-squared, Adjusted R-squared, Mutiple R, and standard error and what these say about how good the regression is for predicting Revenue from the independent variables. Write he model, the equation Next interpretation of the 4 slopes. Which of these variables decrease revenues and which increase revenues? Use the proper units when you do the interpretations. Take care to interpret slopes for dummy variables appropriately. Tests including hypotheses and confidences for the entire equation and each variable separately, 5 sets of tests in all. State hypotheses and write a one sentence interpretation for each of the five. Use α =.05 for all. Should any terms be dropped? If so, which ones and why? Check the assumptions of linearity for JetFuel and DPI (no need for the 2 dummy variables), This is Linearity, independence, Normality, and constant variability. All plots are given to you in the Residuals tab in the excel results file. PHStat does not create the linearity plots. Write a statement detailing what you found and recommendations for addressing any issues present. A statement explaining the results of the 95% prediction interval. Now test statistically if there is evidence of an interaction for this by adding the interaction term Flights x Airtran and run the regression with all the terms. Explain the results and if this suggests you should add the interaction term to your model. Don't forget to explain why or why not! Make sure you include relevant excel results you used for each part above. ( 6 pts ) Note: writing a case report like this may be a problem on the final exam. - R-squared: R2=0.9438, 94.38% of variation in revenue is explained by the variation in JetFuel, DPI, Recession, and Airtran. - Adjusted R-squared: 0.9348, 93.48% of the variation of the revenue is explained by variation of Jet-Fuel, DPI, Recession, Airtran. - Multiple R: 0.9715, 97.15% of the relationship with revenue has to do with the variables Jet-Fuel, DPI, Recession, Airtran. - Standard Error: 192.2927, the data can vary with a range of positive or negative 192.2927 million. Y = -10322 + 60.35(x) + 1.3(x) - 251(x) + 1119(x) + or - 192.3
Ho B1=B2=B3=B4=0 H1 One of the slopes not equal to zero H0: B1 = 0 Fuel is not related to Revenue. H1: B1 ≠ 0 Fuel is related to Revenue. P-value is above 0.05, there is insufficient evidence to reject the null hypothesis. H0: B1 = 0 DPI is not related to Revenue. H1: B1 ≠ 0 DPI is related to Revenue. P-value is below 0.05, so we can reject the null hypothesis. H0: B1 = 0 Recession is not related to Revenue. H1: B1 ≠ 0 Recession is related to Revenue. P-value is below 0.05, so we can reject the null hypothesis. H0: B1 = 0 Airtran is not related to Revenue. H1: B1 ≠ 0 Airtran is related to Revenue. P-value is below 0.05, so we can reject the null hypothesis. It was hypothesized that fuel price, DPI, Merger, and recession would not affect revenue. There is significant evidence to reject the null hypothesis. The significant F is at 0 which is below the level of significance 0.05. I am 99.99% confident that one of the slopes is not equal to zero. 94% of the increase or decreases in revenue are attributed to the increase or decrease in the independent variables. When you adjust for fuel price, DPI, recession, and mergers (R2) and the sample size the percentage is 93% The slopes for the independent variables indicate (coefficients) If fuel was free, no DPI, no merger, and no recession the income would be -10 million, and for every dollar you increase the fuel price, the revenue will increase by 60 million. Similarly for every billion dollars of DPI, the revenue will increase by 1.3 million, and if we had a merger our income would increase by 118 million dollars and if there was a recession, the revenue would decrease by 251 million dollars.
For the given values of the problems equation, when JetFuel = 3.07, DPI = 10337, Recession = 0 and AirTran = 1. The revenue for the company would be 4 million dollars. To validate this model I will check the assumptions of Linearity, Independence, Normality, and equal Variances. The assumption of linearity is valid: there are no patterns of a Parabola (smile, frown. To verify independence in the model I checked the Durban Watson it elicited a number above 1.3. The Durbin Watson was 1.79 which was above 1.3 and below 4. The assumption of independence is met. To verify the assumption of normality I checked skewness and kurtosis. The skewness and Kurtosis are both within the normal range between -1 and 1. The skewness was at -0.16 and the kurtosis was - 0.62. To validate equal variability, I checked the residuals plotted against predicted data. There was no wedge-shaped patterns indicating the data is equally variable. The overall error of the model (standard deviation) was 192 million dollars. The independent variable, DPI, Merger, and recession all had p values below the level of significance which is 0.05. Indicating that all the variables should be included in the model. However, the variable fuel price did not have a p value below 5, so it should be removed from the model. The variance inflation factors were all below 5 indicating multi collinearity is not a factor in the model and nothing needs to be removed. Sample size was 30 so normality of data had been assumed. we are 95% confident that the revenue it will fall between the interval of 3996.604 million and 4871.589 million Regression Analysis Regression Statistics Multiple R 0.9715 R Square 0.9438 Adjusted R Square 0.9348 Standard Error 192.2927 Observations 30 ANOVA
Your preview ends here
Eager to read complete document? Join bartleby learn and gain access to the full version
  • Access to all documents
  • Unlimited textbook solutions
  • 24/7 expert homework help