Chapter 9:

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Chapter 9:. Input Use and Demand for Inputs. Key Topics. Derived demand for inputs Revenue concepts related to input use Total revenue product (TRP) Average revenue product (ARP) Marginal revenue product (MRP) Profit-maximizing input level Profit-max input rule (MRP = input P) - PowerPoint PPT Presentation

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Chapter 9:

Input Use and Demand for Inputs

Key Topics

1. Derived demand for inputs

2. Revenue concepts related to input usea. Total revenue product (TRP)

b. Average revenue product (ARP)

c. Marginal revenue product (MRP)

3. Profit-maximizing input levela. Profit-max input rule (MRP = input P)

b. Input demand curve

c. Shifts in factor demand curves

Derived Demand

The demand for resources (inputs) is dependent on (or derived from) the demand for the outputs those resources can be used to produce.

Input & Output Decisions

Related via production function

q

q*

L* L

TP

Q* = profit-maximizing q L* = profit-maximizing L

Revenue Concepts that are functions of input usage

Total Revenue Product (TRP)Average Revenue Product (ARP)Marginal Revenue Product (MRP)

Revenue Products

Total Revenue Product

= TRP

= TP x P

= paired observations on the $ value of output and physical units of a variable input

Revenue Products

Average Revenue Product

= ARP

= AP x P

= revenue per unit of input

Revenue Products

Marginal Revenue Product

= MRP

= MP x P (= MR*)

= additional revenue per unit of additional input

*for competitive firm

Total RevenueProduct ($)

Average &Marginal RevenueProduct ($)

TP x P = TRP

AP x P = ARP

Input a

MP x MR = MRP

Input a

0

0

A

B C

a1 a2 a3

a1 a2 a3

Profit-Maximizing Input Level

Keep using an input up to the point where the additional revenue from the last additional unit equals the additional cost

MRP = input P

Labor Price (= w)

$

P

S

DL

$

L

MktFirm

P = w

Profit-Maximizing Input Level

$

$

LL*

TRP

TCπ*L*

LMRP

wARP

Find D for Variable Input (e.g. L)

$

ARP

W3

W2

W1

MRP

LL3 L2 L1

Increased D for Labor (examples)

$

w

w1

w2

MRP

LL1 L2

Increased D for Labor (examples)

$

P ofOutput

LL1 L2

w P2 > P1

MRP2 (P2)

MRP1 (P1)

Increased D for Labor (examples)

$

MP

MP2 > MP1

w

L

MRP2 (MP2)

MRP1 (MP1)

L1 L2

Profit-Max Input Rule = Profit-Max Output Rule

MRP = MFC MPL ∙ MR = w

MR = w / MPL

MR = MC

Profit Max Input Side = Profit Max Output Side

TPq

q*

LL*

Profit Max Input Side = Profit Max Output Side

$

w

MRP

LL*

Profit Max Input Side = Profit Max Output Side

$

MC

MR

qq*

Other Input Economics Applications

1. Professional athletes (salaries)

2. Land (rent and usage)

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