In: Statistics and Probability
6. Recently, fixed mortgage rates have been at historical lows due to the housing slowdown. The data table linked below shows the30-year fixed average mortgage rate for the month of December every year between 1987 and 2010.
Year Rate_(%)
1987 11.09
1988 11.04
1989 10.17
1990 9.93
1991 8.57
1992 8.3
1993 7.25
1994 9.04
1995 7.21
1996 7.06
1997 7.07
1998 6.84
1999 7.65
2000 7.74
2001 7.07
2002 6.84
2003 6.94
2004 6.79
2005 7.02
2006 6.82
2007 6.63
2008 5.88
2009 5.64
2010 5.4
b. Forecast the average December mortgage rate in 2011 using a trend projection (Round to two decimal places as needed.)
c. Calculate the MAD for this forecast. (Round to two decimal places as needed.)
d. Determine the Durbin–Watson statistic (Round to two decimal places as needed.)
e. Identify the critical values. (Round to two decimal places as needed.)
ΣX | ΣY | Σ(x-x̅)² | Σ(y-ȳ)² | Σ(x-x̅)(y-ȳ) | |
total sum | 47964 | 183.99 | 1150 | 56.4 | -224.23 |
mean | 1998.50 | 7.67 | SSxx | SSyy | SSxy |
sample size , n = 24
here, x̅ = Σx / n= 1998.50 ,
ȳ = Σy/n = 7.67
SSxx = Σ(x-x̅)² = 1150.0000
SSxy= Σ(x-x̅)(y-ȳ) = -224.2
estimated slope , ß1 = SSxy/SSxx = -224.2
/ 1150.000 = -0.1950
intercept, ß0 = y̅-ß1* x̄ =
397.3303
so, regression line is Ŷ =
397.3303 + -0.1950 *x
...............
Predicted Y at X= 2011
is
Ŷ = 397.33030 +
-0.194978 * 2011 =
5.2290
.................
MAD = 0.5835
.................
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