In: Statistics and Probability
Number of Certified Organic Farms in the United States, 2001–2008 |
|
Year | Farms |
2001 | 5,974 |
2002 | 6,315 |
2003 | 7,032 |
2004 | 7,006 |
2005 | 7,486 |
2006 | 8,368 |
2007 | 9,932 |
2008 | 11,165 |
(a) Use Excel, MegaStat, or MINITAB to fit three trends (linear, quadratic, exponential) to the time series. (A negative value should be indicated by a minus sign. Do not round the intermediate calculations. Round your final answers to 2 decimal places.)
Exponential | yt = 5256.1e .0861x |
(b) Use each of the three fitted trend equations to make numerical forecasts for the next 3 years. (Round the intermediate calculations to 2 decimal places and round your final answers to 1 decimal place.)
t | Exponential | ||
9 | |||
10 | |||
11 | |||
I am having issue predicting the future trendlines.I got 11407.7, 12433.4, and 13551.4 and these were incorrect. Can you please help me learn what I am doing wrong.
a)
for exponential
Year | Farms | t | ln y |
2001 | 5,974 | 1 | 8.695172 |
2002 | 6,315 | 2 | 8.750683 |
2003 | 7,032 | 3 | 8.858226 |
2004 | 7,006 | 4 | 8.854522 |
2005 | 7,486 | 5 | 8.92079 |
2006 | 8,368 | 6 | 9.03217 |
2007 | 9,932 | 7 | 9.203517 |
2008 | 11,165 | 8 | 9.320539 |
SUMMARY OUTPUT | |||||
Regression Statistics | |||||
Multiple R | 0.969205598 | ||||
R Square | 0.939359491 | ||||
Adjusted R Square | 0.92925274 | ||||
Standard Error | 0.057858065 | ||||
Observations | 8 | ||||
ANOVA | |||||
df | SS | MS | F | Significance F | |
Regression | 1 | 0.311134412 | 0.311134412 | 92.94376074 | 7.13297E-05 |
Residual | 6 | 0.020085334 | 0.003347556 | ||
Total | 7 | 0.331219746 | |||
Coefficients | Standard Error | t Stat | P-value | Lower 95% | |
Intercept | 8.56713967 | 0.045082641 | 190.0318949 | 1.4327E-12 | 8.456826422 |
t | 0.08606952 | 0.008927693 | 9.64073445 | 7.13297E-05 | 0.064224241 |
e^(8.5671) = 5256.074
y^= 5256.074 e^(0.08607 t)
t | forecast |
9 | 11404.52341 |
10 | 12429.58585 |
11 | 13546.78305 |
rounding to 2 decimal
t | forecast |
9 | 11404.52 |
10 | 12429.59 |
11 | 13546.78 |