Question

Number of Certified Organic Farms in the United States, 2001–2008

Year Farms


2001 6,231


2002 6,574


2003 7,237


2004 7,211


2005 7,701


2006 8,581


2007 10,302


2008 11,796


Click here for the Excel Data File


(a) 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.)


(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.)

Answer 1

ŷ = 739.49X + 4876.43

y = 6755.98 - 388.24x + 125.30x²

y = 5428.98(1.09)^x

B.)

Linear:

ŷ = 739.49(9) + 4876.43

y = 11531.8

Year 2010 ; x = 10

y = 739.49(10) + 4876.43

y = 12271.3

Year 2011 ; x = 11

y = 739.49(11) + 4876.43

y = 13010.8

Quadratic :

Year 2009 ; x = 9

y = 6755.98 - 388.24(9) + 125.30(9^2)

y = 13411.1

Year 2010 ; x = 10

y = 6755.98 - 388.24(10) + 125.30(10^2)

y = 15403.6

Year 2011 ; x = 11

y = 6755.98 - 388.24(11) + 125.30(11^2)

y = 17646.6

Exponential:

Year 2009 ; x = 9

y = 5428.98(1.09)^9

y = 11791.2

Year 2010 ; x = 10

y = 5428.98(1.09)^10

y = 12852.4

Year 2011 ; x = 11

y = 5428.98(1.09)^11

y = 14009.1

Explanation:

X :

1

2

3

4

5

6

7

8

Y:

6231

6574

7237

7211

7701

8581

10302

11796

Using the online linear regression calculator :

The linear trend :

ŷ = 739.49X + 4876.43

Where x = year

With 2006 representing 1 ; and so on

Slope = m = 739.49

Intercept (c) = 4876.43

y = predicted variable

The quadratic model:

General form:

y = A + Bx + Cx²

y = 6755.98 - 388.24x + 125.30x²

The exponential model:

y = AB^x

y = 5428.98(1.09)^x

B.) Next three years :

Year 2009 ; x = 9

Year 2010 ; x = 10

Year 2011 ; x = 11

Linear:

ŷ = 739.49(9) + 4876.43

y = 11531.8

Year 2010 ; x = 10

y = 739.49(10) + 4876.43

y = 12271.3

Year 2011 ; x = 11

y = 739.49(11) + 4876.43

y = 13010.8

Quadratic :

Year 2009 ; x = 9

y = 6755.98 - 388.24(9) + 125.30(9^2)

y = 13411.1

Year 2010 ; x = 10

y = 6755.98 - 388.24(10) + 125.30(10^2)

y = 15403.6

Year 2011 ; x = 11

y = 6755.98 - 388.24(11) + 125.30(11^2)

y = 17646.6

Exponential:

Year 2009 ; x = 9

y = 5428.98(1.09)^9

y = 11791.2

Year 2010 ; x = 10

y = 5428.98(1.09)^10

y = 12852.4

Year 2011 ; x = 11

y = 5428.98(1.09)^11

y = 14009.1