Mastodon
List
Figure 1: An example of an indifference map wi...

 

[print_link]

Introduction

The last lecture introduced the course. This lecture re-introduces you to some of the concepts you learned last year in Dr. Lenihan's class. The concept of utility has a long and convoluted history in economics, and has been discussed since at least 1748. The idea of choice theory is to make a statement about what choices a rational person should make, based on their preferences, among competing alternatives. It will turn out that people's desires are infinite, while their budgets are often much more limited. The constraints individuals work under, combined with their prestated preferences, turn out to be the important factors in creating the theory of choice. First, let's talk about utility. 



Important Concepts. Budget constraint, utility function, indifference curve, marginal utility, marginal rate of substitution

Definition. Utility is the satisfaction a person receives from their economic activities.

To get a measure of utility, we will need to make some assumptions about the world. 

  1. Ceteris Paribus. Holding other factors constant, we can think about measuring utility because other choices outside the ones we are considering are not affected by the choices we make now.
  2. Utility Function. There need to be at least 2 goods in a model of economic choice. Most of the time there are many more. The mechanism we use to describe how the consumer combines their utility is called the utility function. For each combination of goods, call them and , the function pumps out a level of utility, , holding everything else constant. 
Utility everything else) 


Assumptions about Preferences

  1.  Transitivity. If there are three goods, , , and , then our consumer can choose between them. If he prefers to , and prefers to , then he must prefer to
  2. Completeness. For any list of goods we give him, our consumer has to be able to make a choice between those goods, and rank them, because the assumption of transitivity must hold.
  3. More Preferred to Less. If the good is normal, so if your income increases, you'll demand more of it, you will always prefer more stuff to less stuff. 


Indifference Curves

These are tricky little beasts, so it is wise to spend some time working on drawing them.

Think of an indifference curve like a contour map of a mountain. The indifference curve represents a set of points (called a locus) where, for each consumer, each point represents a combination of goods which makes them equally happy. The consumer will always want to be higher up the mountain of happiness, so to speak, but if they have to stay there, then they will be indifferent between the alternatives on that line. Click the image below to get an excel file to manipulate. In class we'll use a mathematica demonstration

Choosing between Alternatives

Diminishing Marginal Rate of Substitution. The MRS is the slope of the indifference curve, and it encapsulates the idea that you will be willing to give up a certain number of units of to get more units of on the same indifference curve. The MRS is the ratio between the marginal utilities () of each good, and , so 



The MRS stops moving along the indifference curve when ratio between the prices of each good, and is equal to the value of the MRS. We'll have something like



Because , it follows that 



All this says is that the ratio of the extra utility for consuming one more unit of either good to its price should be the same for each good. Now, where do we get the prices from? We get them from the budget constraint

Budget Constraint. The budget constraint shows the combinations of the two goods the consumer can afford, given that they have a fixed amount of income. The budget curve is downward-sloping because to get more of good , you're going to have to give up some of good

The budget constraint looks like this: 

We'll put the two diagrams together in class using the mathematica demonstration. 

Exercises to test your understanding in the book: Ex. 2.1, 2.2, 2.9.

In the next lecture, we'll look at individual demand curves. 

One Response to “EC4004, Economics for Business, Lecture 2: Utility”

  1. Anna O'Leary

    lectures r great, at least i'm not falling asleep. explanations r in good English so easy to understand. suggestion: please bring fruit next time for ur experiment instead of Crunchy, coz it would be much healthier! Your r doing a great job, very good approach to presenting lectures, very enjoyable!!!!!

  Posts

1 2 3 154
December 10th, 2019

Using Social Media to Boost your profile

My talk for the social media summit is here. 

November 5th, 2019

Innospace UL talk

Thanks for the invitation to speak, the whole talk is here. 

October 9th, 2019

Understanding the macroeconomy podcast

I really enjoyed my interview with Dr Niall Farrell of the Irish Economics Podcast. You can listen to it here:

September 15th, 2018

Identifying Mechanisms Underlying Peer Effects on Multiplex Networks

New paper with Hang Xiong and Diane Payne just published in JASS: Abstract: We separately identify two mechanisms underlying peer […]

March 24th, 2018

Capital inflows, crisis and recovery in small open economies

Our latest paper, and my first with my Melbourne School of Government affiliation (plus my UL one, of course) is […]

March 7th, 2018

Southern Charm

What's it like working at Australia's number one university, ranked 23rd in the world for social sciences? It's pretty cool, […]

February 7th, 2018

Freedom interview

I did an interview for an app I love using called Freedom. Basically I pay them to block off the […]

December 10th, 2017

Marian Finucane Interview

I did a fairly long interview about the experience of moving to Australia with my family. You can listen here.

November 17th, 2017

Increasing wages for macroeconomic stability

My first piece for the conversation is here. I'm arguing the economy would benefit from wage increases, paid for from […]

November 14th, 2017

Health Workforce Planning Models, Tools and Processes: An Evidence Review

Below is my recorded talk, here are my slides, and the handout for the 4th Global Forum on Human Resources for […]

October 5th, 2017

Aalborg Keynote

My talk from the fourth Nordic Post Keynesian conference is up. The full list of keynotes is here.

October 1st, 2017

AIST Debt and Demography talk

(Apparently Limerick is in the UK now!)

September 7th, 2017

My AIST Keynote: Europe Exposed

In which a camera man faints halfway through--he's OK though, I checked afterwards!

July 22nd, 2017

MacGill Summer School Speech

My speech at the MacGill Summer School is here. Thanks to Joe Muholland for inviting me to speak.

May 25th, 2017

Business Post Articles

All my Sunday Business Post articles (back to 2014/5, when I joined the paper) are available here, behind a paywall, and […]

@barrd on Mastodon