Elasticity

  1. Price Elasticity of Demand (Ed)

is a measure of how much Qd of a good changes when price of good changes.

Formula: image (16)

% change in Qd / % change in Price

% change in Qd =

[(New Qd - original Qd) / (New Qd + original Qd)/2] x 100

% change in Price =

[(New price - original price) / (New price + original price)/2] x 100

Levels of Elasticity

Elastic image (17)

When Ed > 1

Unit Elastic image (18)

When Ed = 1

Inelastic image (19)

When Ed < 1

Demand Curve image (20)

Elastic at any price above midpoint (B)

Unit elastic at midpoint (B)

Inelastic at any price below (B)

2 influences:

Availability of substitutes

Propotion of income spent

Hard to find

The longer the time elapsed since price change

Readily available

How good is defined

Elastic

Inelastic

= more elastic demand

Narrow

Broad

Elastic demand

Inelastic demand

The greater the %, the more elastic

Relationship to Total Revenue (RV)

TR = Price x Quantity

If elastic

a given % rise in Price

Price & TR change in opposite direction

creates a larger % decline in Qd

total revenue decreases

If inelastic

a given % rise in Price

Price & TR change in same direction

total revenue increases

creates a smaller % decline in Qd

If unit elastic

when Price change doesn't change TR

  1. Price Elasticity of Supply (Es)

is a measure oh how much Qs of a good changes when the price of good changes

Formula image (21)

% change in Qs

% change in Price

% change in Qs / % change in Price

[(New Qs - original Qs) / (New Qs + original Qs) / 2 x 100

[(New Price - original Price) / (New Price + original Price) / 2 x 100

Level of Elasticity

Unit Elastic image (23)

Inelastic image (24)

Elastic image (22)

% change in Qs > % change in Price

Es > 1

% change in Qs = % change in Price

Es = 1

% change in Qs < % change in Price

Es < 1

Perfectly Elastic image (25)

Perfectly Inelastic image (26)

2 Influences

Production possibilities

Storage possibilities

Elastic

Inelastic

goods produced with constant opportunity cost

goods produced in fixed quantity

Elastic

Inelastic

storable goods

non-storable goods

cost of storage in the MAIN influence on supply of strorable good

  1. Income Elasticity

is a measure of how much demand for a good changes when income changes, other things remaining the same.

Formula

% change in Qd / % change in income

  1. Cross Elasticity of Demand (CEd)

is a measure how much the demand for a good changes when the price of a substitute or complement changes

Formula

% change in Qd / % change in Price of substitute/complement

CEd for Substitute

if positive image (28)

a fall in Price of substitute causes a decreases in Qd

Qd of good & price of substitute change in same direction

CEd for Complement

If negative image (29)

a fall in the price of a complement causes an increase in Qd of the good

Qd of good & price of substitute change in opposite directions