The Lorenz Curve displays the actual income or wealth distribution of an economy. The concept was brought up by the American economist Max O. Lorenz in 1905. The curve represents a graphical representation of the income or wealth distribution of an economy or country. That is, it shows the proportion of income earned or wealth possessed by any given percentage of the population. In the case that everyone has approximately the same wealth, we have a very equal society. While in a case where few own the majority of wealth, we have high inequality. The following figure depicts the Lorenz curve for three economies with varying degrees of inequality.

# Category Archives: Macroeconomics

# Tobin’s q-Investment Theory

In the 60s and 70s, economists including Nicholas Kaldor and James Tobin came up with an alternative investment theory: the q-investment theory, sometimes also referred to as Tobin’s q-investment theory. At its core, Tobin’s q theory of investment relates fluctuations in investment to changes in the stock market. Although the theory gained popularity only in the 70s, first elements of the theory can already be found in works of John Maynard Keynes. In his *General theory of employment, interest and money*, Keynes mentioned already that investment might be linked to the stock market.

# The Neoclassical Theory of Investment

Dale W. Jorgenson contributed to the development and understanding on the neoclassical investment theory. In the following post I will try to outline and discuss the neoclassical investment theory in simply words. At its heart, Jorgenson’s investment model bases on the idea that there exists an optimal capital stock. Economic actors, such as firms, invest and disinvest in order to reach the optimal capital stock. Continue reading The Neoclassical Theory of Investment

# General Principles for Specifying a Dynamic General Equilibrium Model

The Dynamic General Equilibrium Model (DGE) is characterized by various features. Firstly, a DGE is **dynamic**, which means that it considers an economy over time. Second, it considers a **general** economy, which implies that the modelled economy is fully specified. Lastly, the model relies on an **equilibrium** concept. Continue reading General Principles for Specifying a Dynamic General Equilibrium Model

# Capital Adjustment Costs

Understanding investment activity in an economy is not trivial. The erratic nature of firm level investment activity is somewhat of a mystery to me and it took me quite some time to get a vague idea of what could be the generating process behind such an erratic behavior. I think understanding capital adjustment costs was the key to understand why it can be rational for firms to invest in a spasmodic way. In this post I would like to shortly summarize part of what I learnt so far and list different types of capital adjustment costs found in the literature.

# Balance Statistic

The following article tries to explain the *Balance Statistic* sometimes referred to as *Saldo* or *Saldo Statistic. *It is used as a quantification method for qualitative survey question. The benefit of applying the *Balance Statistic *arises when the survey is repeated over time as it tracks changes in respondents answers in a comprehensible way. The *Balance Statistic* is common in Business Tendency Surveys.

# Log-Linearizing

Log-Linearizing

What exactly is happening when we linearize a model? Well, the answer is simple, we basically approximate non-linear equations with linear once. In context of macroeconomics we may have models which are non-linear. Thus in order to solve them there is need to put them in a linear form. In the following we are going to see how to log-linearizing a model by the means of a (very) simple example. Continue reading Log-Linearizing

# Rational Expectations

Rational Expectations

When talking about rational expectations all of us know immediately what we mean, this was my belief until some months ago. However it seems to me that many people have a vague idea about the concept, but they fail to clearly state the most important underlying assumptions.