In: Statistics and Probability
The following are the average scores on the mathematics part of the Scholastic Aptitude Test (SAT) for some of the years from 1994 to 2009.
Year, SAT Score
1994 504
1996 508
1998 512
2000 514
2002 516
2004 518
2005 520
2007 515
2009 515
Assuming a simple linear regression model, predict the average scores in 1997, 2006 and 2008
Following is the output of regression analysis:
SUMMARY OUTPUT | ||||||
Regression Statistics | ||||||
Multiple R | 0.799131184 | |||||
R Square | 0.63861065 | |||||
Adjusted R Square | 0.5869836 | |||||
Standard Error | 3.182824921 | |||||
Observations | 9 | |||||
ANOVA | ||||||
df | SS | MS | F | Significance F | ||
Regression | 1 | 125.3096009 | 125.3096009 | 12.36969088 | 0.00976622 | |
Residual | 7 | 70.91262136 | 10.13037448 | |||
Total | 8 | 196.2222222 | ||||
Coefficients | Standard Error | t Stat | P-value | Lower 95% | Upper 95% | |
Intercept | -1047.614887 | 443.8867047 | -2.360095213 | 0.050334237 | -2097.240153 | 2.010379887 |
Year, X | 0.779935275 | 0.22175792 | 3.517057134 | 0.00976622 | 0.255561119 | 1.304309431 |
The simple linear regression analysis is:
y' = -1047.61+0.78x
The predicted value for x = 1997 is
y' = -1047.61+0.78*1997 = 510.05
The predicted value for x = 2006 is
y' = -1047.61+0.78*2006 = 517.07
The predicted value for x = 2008 is
y' = -1047.61+0.78*2008 = 518.63