In: Statistics and Probability
The total expenses of a hospital are related to many factors. Two of these factors are the number of beds in the hospital and the number of admissions. Data were collected on 14 hospitals, as shown in the following table:Find the best regression model to predict the total expenses of a hospital. Discuss the accuracy of this model. Should both variables be included in the model? Why or why not?
Hospital | # Beds | Admissx1000 | Total Exp x$1mil |
1 | 120 | 77 | 57 |
2 | 336 | 160 | 127 |
3 | 310 | 230 | 157 |
4 | 55 | 33 | 24 |
5 | 30 | 19 | 14 |
6 | 190 | 155 | 93 |
7 | 110 | 53 | 45 |
8 | 40 | 6 | 6 |
9 | 210 | 159 | 99 |
10 | 25 | 18 | 12 |
Regression Statistics | ||||||||
Multiple R | 0.997641 | |||||||
R Square | 0.995288 | |||||||
Adjusted R Square | 0.993942 | |||||||
Standard Error | 4.12342 | |||||||
Observations | 10 | |||||||
ANOVA | ||||||||
df | SS | MS | F | Significance F | ||||
Regression | 2 | 25139.38 | 12569.69 | 739.2809 | 7.18E-09 | |||
Residual | 7 | 119.0181 | 17.00259 | |||||
Total | 9 | 25258.4 | ||||||
Coefficients | Standard Error | t Stat | P-value | Lower 95% | Upper 95% | Lower 95.0% | Upper 95.0% | |
Intercept | -0.62223 | 2.149332 | -0.2895 | 0.780585 | -5.70459 | 4.46013 | -5.70459 | 4.46013 |
X Variable 1 | 0.1953 | 0.035172 | 5.552634 | 0.000858 | 0.11213 | 0.27847 | 0.11213 | 0.27847 |
X Variable 2 | 0.3975 | 0.051374 | 7.737414 | 0.000113 | 0.27602 | 0.518979 | 0.27602 | 0.518979 |
Total expenses=-0.62223+0.1953 beds+0.3975 admission
Here R2=0.99 i.e. 99% .The model is 99% good fit. The 99% variation in the total expenses explained by the regressors.
For bed p-value is 0.000858 <0.05 and for admission 0.000113<0.05.
Therefore number of bed and number of admission both are contributing significantly. So both variables should included in the model.