The SSNIP Test

Each product that exists can be classified into a market in which it competes with other products for the attention of consumers. For instance, apples might be considered a snack-fruit and compete with items including pears and bananas. In other words, if the price of apples increased then demand would substitute towards one of these other products. The market for apples, would thus include these other fruits which substitution can easily happen.

Such substitution means that apple producers are restricted in their ability to increase prices. Increasing prices too much would result in this demand substitution towards other products.

On the other hand, other products might have a more restricted market. [...]

Price Discrimination and Social Welfare

Standard texts of price discrimination see it as beneficial in a social welfare sense: consumer surplus is transferred to producer surplus, but the fact that quantity increases is good for social welfare (as it reduces the deadweight loss triangle). Interestingly, this isn’t the whole story. Tullock pointed out, a number of years ago, that social welfare loss can originate from the rent-seeking activities of those that are trying to capture these rents.

For instance, in a monopoly setting, standard economic theory would say that the cost of monopolies comes from the reduction in quantity sold (as a result of higher prices), leading to a loss of social welfare. [...]

Investment Functions

In this article we explain the fundamental factors determining investment decisions of firms, which comprise the investment function. By determining the structure of the investment function we can hypothetically estimate this and thus predict how much a given firm ought to be investing, given economic fundamentals. This is interesting because we could then aggregate such functions – i.e. add up each firm-specific investment equation – to get a measure of what total investment by private firms in the economy ought to be investing. By comparing this amount with actual levels of investment we can derive a measure of the investment gap. [...]

Marshallian Industrial Districts and the Rise of the Internet

Recently I attended a Conference for the 40th Anniversary of the Cambridge Journal of Economics where a talk was given on “Industrial Districts, Organisation & Policy”. This article is a summary of some of the discussion from this talk as well as my further thoughts on extending Marshallian Industrial Districts to incorporate the internet.

What is a Marshallian Industrial District?
A Marshallian Industrial District is normally considered a clustering of firms in a similar industry operating from a certain geographic area. Being close to many other firms in the same industry allows a number of benefits, sometimes called benefits of agglomeration or Marshallian atmospheric externalities. [...]

Strategic Pricing

This article will explore an overview of pricing strategy. We begin by explaining the simple Cournot and Bertrand games, which are game theoretic analyses of a firm’s pricing strategy. With this information we proceed by explaining what strategic complementarities and substitutes are before looking at a paper by Fudenberg and Tirole entitled “The Fat-Cat Effect, the Puppy-Dog Ploy, and the Lean and Hungry Look”.

Cournot Game
In this scenario we have (at least) two firms who compete on the amount of output they produce, choosing the quantity simultaneously and independently whilst taking the output decision of the other firms as given. [...]

What is the WACC?

The weighted average cost of capital (WACC) is simply an average cost of the two types of capital: debt and equity. It tells us the amount an investor would need in compensation to invest in a project. Therefore if we were to offer a lower return than the WACC, we would find that we have no investors; a return greater than WACC would lead to a situation where we have excess demand for our project.

To theoretically calculate the rate of return on a project we would need to compare it with existing returns on projects which have similar risk characteristics, and then set the return similar to these projects to ensure that we can attract finance. [...]


Economists have an affinity for the concept of efficiency, but often this is quite a vague concept. In this article we attempt to explain a few different types of efficiency/inefficiencies and show the different situations in which the word “efficiency” should be used.

Before we start it is important to remember why inefficiencies are bad and why a healthy economy should strive to be efficient. Lionel Robbins defined economics as the study of the allocation of scarce resources. Therefore an economist’s job is to ensure that these scarce resources are used to their best potential, therefore waste should be minimised and this can be achieved through efficient use of materials. [...]

What is a Cobb-Douglas Function?

The Cobb-Douglas function has many applications in economics; from being a well-behaved preference in microeconomics to a production function in macroeconomics. It is named after Paul Douglas, an American Congressmen who was researching labour and capital shares and asked Charles Cobb, a mathematician, for help in formulating this into a function. In this article we will explore its use as a production function.


In its simplicity, a CD (Cobb-Douglas) function is just a function. A function, in mathematical jargon, transforms an input into a single output: it is a one-to-one mapping. For example Y=2X is a simple function. X is the independent variable and Y is the dependent variable, because Y is determined by whatever the value of X is. [...]

Predictably Irrational

I have just finished reading Predictably Irrational, a book by Dan Ariely on why economic thinking is flawed due to its failure to include behavioural economic concepts. In economics the actions of people are summed up by Homo Economicus, an imaginary figure that is completely rational and bases all its actions upon these rational foundations. Obviously not all humans are as rational as Homo Economicus, and this causes inconsistencies in economic models.

Dan Ariely argues that if we use findings from behavioural economics (a branch of economics that incorporates psychology) and mould these into our economic models, then we will improve our models and will thus have a better understanding of how the economy actually works. [...]