Indifference Curves and Giffen Goods

New to the A2 CIE syllabus is indifference curves and my A2 class recently had a multiple-choice question concerning indifference curves and giffen goods. A giffen good occurs when a rise in price causes higher demand because the income effect outweighs the substitution effect.

Suppose you have a very low income and eat two basic food stuffs rice and meat. Meat is a luxury and is much more expensive than rice. If rice increased in price, your disposable income is effectively reduced significantly therefore, you buy less meat, to compensate for less meat you buy more rice to gain enough calories. Source: www.economicshelp.org

Griffen good and indifference curves

indiff-giffen

  • Good B falls in price – hence budget line moves from: 50 A – 30 B to: 50 A – 60 B.
  • The move from point J to point K is the substitution effect which = +16
  • The move from point K to point L is the income effect which = -20
  • These make up an overall move from point J to point L is the price effect (substitution effect + income effect) = -4

As income effect is negative, substitution effect positive and overall price effect negative Good B is a giffen good.

Summary of income and substitution effects of price changes

sub-income-effect

Go to eLearn Economics for more notes on Indifference Curves.

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