Suppose we have data for the unit costs of four agricultural products from 1998 to 2008.
|
Year
|
Pork ($/lb)
|
Beef ($/lb)
|
Chicken ($/lb)
|
Duck ($/lb)
|
|
1998
|
1.20
|
2.10
|
1.50
|
2.81
|
|
1999
|
1.45
|
2.40
|
1.35
|
3.10
|
|
2000
|
1.35
|
2.67
|
1.40
|
3.50
|
|
2001
|
1.23
|
2.78
|
1.56
|
3.67
|
|
2002
|
1.40
|
2.34
|
1.58
|
3.30
|
|
2003
|
1.20
|
2.55
|
1.53
|
3.52
|
|
2004
|
1.50
|
2.65
|
1.38
|
3.68
|
|
2005
|
1.55
|
2.87
|
1.62
|
3.70
|
|
2006
|
1.70
|
2.44
|
1.68
|
3.71
|
|
2007
|
1.60
|
2.60
|
1.70
|
3.73
|
|
2008
|
1.68
|
2.62
|
1.65
|
3.53
|
Use Excel or a statistical package to derive the variance-covariance matrix from the data above.