29 July 2017

A simple model of boom and bust

How private sector spending behaviours drive the economy and government budget

In the last two posts we developed simple models of how government money circulates in the economy. In this post, we'll experiment with some of the behaviours encoded in these models in order to elucidate some of the ways in which the government and private sector interact with one another.

In the first model we assumed that the private sector saved a constant fraction of their income. This resulted in a stable aggregate income level and ever-increasing saved wealth. It also meant that the government - which is the monetary authority - had to constantly add money into the economy to counteract this "leakage" of money into savings. As such, the government had a permanent budget deficit and the size of the government "debt" was ever increasing through time, mirroring the private savings.

In the second model we added the ability of the private sector to spend out of their saved wealth. This resulted in larger aggregate incomes and a stabilised level of saved wealth, interpreted to represent the private sector's wealth target. By implication, the government ended up with a balanced budget position and a stable level of debt.

Here, we're going to retain the final form of the model and simply adjust some of the input parameters - specifically, the propensity to spend out of income (\(\alpha_Y\)). First we'll decrease the propensity to spend out of income and then we'll increase it again. This effectively represents a variation in the spending and saving behaviours of the population. We could also adjust the propensity to spend out of savings (\(\alpha_H\)) but we'll stick to just varying \(\alpha_Y\) for the sake of simplicity.

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19 July 2017

A model economy with government money and private wealth target

A self-limiting private sector and a stabilizing economy

This post will describe another complete - but simple - model economy. It follows directly from the previous model and introduces one fairly simple innovation. In the last model the private sector spent a certain proportion of it's disposable income, saving the rest. In this model the private sector spend out of both income and saved wealth. The introduction of spending out of wealth in the only difference. This model is the starting point for the stock-flow consistent models described in Monetary Economics by Wynne Godley & Marc Lavoie (model "SIM").

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03 June 2017

A simple economy with government money

A simple but rigorous accounting of economic flows and sectoral balances through time

This post describes a complete, if very simple, economic model. We'll use the insights and mathematical formulations developed previously (e.g. here, here, and here) but these will be anchored within a wider accounting and modelling framework which helps us to organise our model components and ensure that the model is coherent.

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06 May 2017

Is taxation theft?

Do we have the right to exert our economic power unchecked?

Alex Douglas recently posted an article entitled Taxation is Theft?. As usual, I find what Alex says very compelling but it reminded me of a line of thinking that usually occurs to me when I think about the question of taxation and particularly the moral basis for taxation.

The idea that taxation is theft seems to arise from the idea that the economy is a fair competition and therefore whatever one is able to obtain by selling their labour or employing their captial in this marketplace is justly deserved. The earnings are the rightful property of the individual. The implication is that if the state opts to commandeer some of this property (via taxation), then that is equivalent to theft.

The are many lines of argument one can take on this position, but the question that occurs to me is whether it is true that what we obtain on the market is justifiably earned/deserved. And I am not convinced that it is, or at least I do not think that it follows obviously.

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10 April 2017

Modelling the fiscal multiplier

Some additional considerations for modelling building

This is the third post in a series of posts looking at the fiscal multiplier. Previously, we have examined how the circular flow of money interacts with government spending and taxation (as well as private saving) by considering a mathematical structure called a geometric series. This interpretation of the fiscal multiplier is based around the concept of "spending rounds" which represent successive events in which income received previously is spent onwards, creating new income which is spent in the next round, and so on. Each spending round involves a successively smaller amount of circulating money because a fraction of all income is collected in tax (or saved). Eventually, all of the money has been withdrawn from circulation via taxation (and saving) and the spending stops. In the interim period, the circulation of the ever-reducing money stock produces a total, cumulative amount of income.

This approach is an intuitive way of thinking about sequences of spending. It enables us to conceive of how the money initially introduced by government spending is passed around the economy and what the implications of taxation and saving are. But whilst it arguably does a good job of describing how individual acts of spending follow the receipt of income, it should be recognised that in real economies collective spending does not precede collective income in discrete, ordered stages. Spending and the receipt of incomes arise via an incredibly complex network of millions of overlapping transactions occuring continuously.

The concept of the spending round also leads to questions such as how long it takes for a single spending round to occur, or the number of rounds that should be considered. It seems reasonable, for example, that the number of spending rounds included in any analysis would depend on the time period under consideration. But it is not really clear how spending rounds relate to absolute time. However, it turns out that these concerns can be adequately side-stepped by using a coherent accounting framework. This post attempts to tighten up our understanding of the fiscal multiplier and presents an alternative mathematical derivation which is more conducive to inclusion in more complex models.

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