Using equation (1), calculate what would happen - ceteris paribus - to the demand for lamb if:

(a) The real price of lamb went up by 10p per kg;

(b) The real price of beef went up by 10p per kg;

(c) The real price of pork fell by 10p per kg;

(d) Real disposable income per head rose by £100 per annum.

Are the results as you would expect?

1. How does the introduction of the variable TIME affect the relationship between the demand for lamb and (a) its real price; (b) real disposable income per head?

2. Does lamb appear to be a normal good or an inferior good?

3. What does the negative coefficient of P_B indicate?

i. To what extent is model (3) an improvement on model (2)? 

ii. Use the three equations and also the data given in the table below to estimate the demand for lamb in 2000 and 2010. Which model works the best in each case? Why? Explain why the models are all subject to error in their predictions.

iii. Use model (3) and the data given in the table to explain why the demand for lamb fell so dramatically between 1980 and 2010.