Week 4 - Consumer theory Flashcards
Where does the demand curve come from?
consumers
Where does the supply curve come from?
producers
What are the 3 steps of what bundles of goods makes you best off?
- Preferences
- Budget constraints
- Put them together
What is a consumption bundle
(basket of goods) is a complete list of quantities for all available goods
What is the notation of a typical consumption bundle?
X = (x , x , x )
B C F
Eg A = (2, 5, 1) or A = (2 bananas, 5 coconuts, 1 fish)
What are the x and y axis of the consumption model eg?
eg
x = pizza
y = coke
What are the 3 ways of comparing a consumption bundle by any individual (preferences)?
If bundle A is strictly preferred to bundle B, then A>B
If bundle A is weakly preferred to bundle B, then A≥ B
If the individual is indifferent between A and B, then A~B
What are the three assumptions about individual preferences?
- Completeness
- Transitivity, Reflexivity
- Non-satiation, diminishing marginal utility
What is the completeness assumption?
for any pair of available consumption bundles X and Y, the individual can say whether X≥Y or Y≥X (or both)
What is the transivity assumption?
for any three consumption bundles, X, Y, Z
X≥Y and Y≥Z imply X≥Z
What is reflexivity?
(within transitivity)
for identical consumption bundles, there is no strong preference for either of them X~X
What is the non-satiation assumption?
more is better than less (at least more is no worse than less)
What does it mean if the bundle is further away from the axis on the preference graph
the ‘better’ they are, prefer those bundles (get more quantity)
What is the utility function?
it assigns each consumption bundle an index number of happiness (=total utility)
How can the utility function U(X) be used for any two consumption bundles?
for any two consumption bundles, X and Y, the utility function can be used to extract the individual’s preferences as follows:
if U(X) > U(Y) then the individual strictly prefers bundle X to Y
if U(X) = U(Y) then the individual is indifferent between consumption bundles X and Y
the utility function can take a variety of mathematical forms (to compare different assumption models)
What is the ordinal utility?
means that only the ranking of utility levels has a meaning - the difference between utility levels is meaningless
U(A) = 20 and U(B) = 40 does not mean that the individual prefers bundle B twice as much as A
What does it mean to be indifferent between X and Y?
if you neither prefer X to Y, nor Y to X, you are indifferent between X and Y, and you derive the same utility from both bundles:
U(X) = U(Y)
What shape are indifference curves?
always downward sloping
What is an example of axis on an indifference curve?
Pizza and coke
eg X1 = (3,4) and X2 = (4,3)
make a rectangle, both have utility of 12
all being utility of 12 means this individual is indifferent to all of these consumption models as they have the same utility
Where does the second indifference curve go when it has a greater utility than the other curve?
above, further away the better
higher utility levels lie further outwards (to the origin)
one indifference curve for each utility level
Why cant indifference curves cross example?
Eg
A and B on the same indifference curve A~B
B and C on the same indifference curve B~C
By transitivity A~C
But A is on a higher indifference curve than C
So A>C
What is marginal utility?
the additional utility generated by an additional unit of the good, holding the quantities of all other goods constant
How do you mathematically calculate the marginal utility of a good?
it is the partial derivative of U(x_1,…,x_n) with respect to x
MU_L = ∂U(x_1,…x_n) / ∂x_i