Archive for the 'Teaching' Category

Teaching, teaching

It’s the new academic year.  I’m once again teaching (not lecturing!), this time in EC400, the pre-sessional September maths course for incoming post-graduate students, and EC413, the M.Sc. macro course.

I’m also a new (Teaching) Fellow in the school, which means that a) I’m now a formal academic advisor (my advisees are yet to be determined); and b) I’m technically part of the academic staff at LSE (even though I’m only part-way through my Ph.D.).  That last point gets me access to the Senior Common Room (where the profs have lunch) and into USS, the pension scheme for academics at most UK universities.

Here’s what’s amazing about USS:  It’s a final salary scheme!  I’m honestly amazed that there are any defined-benefit schemes still open to new members.  Well, there you go.  I’m in one now.

In honour of grad students marking exams …

… and since I finished my marking today, here are The Simpsons and PHD Comics on the typical graduate student’s lot in life in May and June:

The short-long-run, the medium-long-run and the long-long-run

EC102 has once again finished for the year.  It occurs to me that my students (quite understandably) got a little confused about the timeframes over which various elements of macroeconomics occur.  I think the reason is that we use overlapping ideas of medium- and long-run timeframes.

In essense, there are four models that we use at an undergraduate level for thinking about aggregate demand and supply.  In increasing order of time-spans involved, they are:  Investment & Savings vs. Liquidity & Money (IS-LM),  Aggregate Supply – Aggregate Demand (AS-AD), Factor accumulation (Solow growth), and Endogenous Growth Theory.

It’s usually taught that following an exogenous shock, the IS-LM model reaches a new equilibrium very quickly (which means that the AD curve shifts very quickly), the goods market in the AS-AD world clears quite quickly and the economy returns to full-employment in “the long-run” once all firms have a chance to update their prices.

But when thinking about the Solow growth model of factor (i.e. capital) accumulation, we often refer to deviations from the steady-state being in the medium-run and that we reach the steady state in the long-run.  This is not the same “long-run” as in the AS-AD model.  The Solow growth model is a classical model, which among other things means that it assumes full employment all the time.  In other words, the medium-run in the world of Solow is longer than the long-run of AS-AD.  The Solow growth model is about shifting the steady-state of the AS-AD model.

Endogenous growth theory then does the same thing to the Solow growth model: endogenous growth is the shifting of the steady-state in a Solow framework.

What we end up with are three different ideas of the “long-run”:  one at business-cycle frequencies, one for catching up to industrialised nations and one for low-frequency stuff in the industrialised countries, or as I like to call them: the short-long-run, the medium-long-run and the long-long-run.

More people have jobs AND the unemployment rate is higher

This is another one for my students in EC102.

Via the always-worth-reading Peter Martin, I notice that the Australian Bureau of Statistics February release of Labour Force figures contains something interesting:  The number of people with jobs increased, but the unemployment rate still went up.  Here’s the release from the ABS:

Employed Persons Unemployment Rate
Australia Feb 2009 Employment Australia Feb 2009 Unemployment Rate



  • EMPLOYMENT increased to 10,811,700
  • UNEMPLOYMENT increased to 561,100
  • UNEMPLOYMENT RATE increased to 4.9%
  • PARTICIPATION RATE increased to 65.4%



  • increased by 1,800 to 10,810,400. Full-time employment decreased by 53,800 to 7,664,200 and part-time employment increased by 55,600 to 3,146,200.


  • increased by 47,100 to 590,500. The number of persons looking for full-time work increased by 44,400 to 426,000 and the number of persons looking for part-time work increased by 2,600 to 164,500.


  • increased by 0.4 percentage points to 5.2%. The male unemployment rate increased by 0.3 percentage points to 5.1%, and the female unemployment rate increased by 0.5 percentage points to 5.3%.


  • increased by 0.2 percentage points to 65.5%.

The proximate reason is that more people want a job now than did in January.  The unemployment rate isn’t calculated using the total population, but instead uses the Labour Force, which is everybody who has a job (Employed) plus everybody who wants a job and is looking for one (Unemployed).


Employment increased by 1,800, but unemployment increased by 47,100, so the unemployment rate ($$u$$) still went up.

Peter Martin also offered a suggestion on why this happened:

We’ve lost a lot of wealth and we’re worried. So those of us who weren’t looking for work are piling in.

I generally agree, but my guess would go further. Notice two things:

  • Part-time jobs went up by 55,600 and full-time jobs fell by 53,800 (the difference is the 1,800 increase in total employment).
  • The number of people looking for part-time jobs went up by only 2,600 and the number of people looking for full-time jobs rose by 44,400 (yes, I realise that there’s 100 missing – I guess the ABS has a typo somewhere).

There are plenty of other explanations, but I think that by and large, the new entrants to the Labour Force only wanted part-time work and found it pretty-much straight away – these are households that were single-income, but have moved to two-incomes out of the concern that Peter highlights.  On the other hand, I suspect that the people that lost full-time jobs have generally remained in the unemployment pool (some will have given up entirely, perhaps calling it retirement).

The aggregate result is that the economy had a shift away from full-time and towards part-time work, although the people losing the full-time jobs are not the ones getting the new part-time work.

The fiscal multiplier

This is mostly for my EC102 students.  There’s been some argument in the academic economist blogosphere over the size of the fiscal multiplier in the USA.  The fiscal multiplier is a measure of by how much GDP rises for an extra dollar of government spending.  There are several main forces in determining it’s size:

  • The Marginal Propensity to Consume (MPC) determines the upper limit of the multiplier.  Suppose that for each extra dollar of income, we tend to spend 60 cents in consumption.  Because the economy is a massive, whirling recycling of money – I spend a dollar in your shop, you save 40 cents and spend 60 cents in the second shop, the guy in the second shop pockets 40% of that and spends the rest in the third shop and so on – one dollar of government spending might produce 1+ 0.6 + 0.6^2 + 0.6^3 + … = 1 / (1 – 0.6) = 2.5 dollars of GDP.
  • The extra government spending needs to be paid for, which means that taxes will need to go up.  For it to be a stimulus now, it’ll typically be financed through borrowing instead of raising taxes now (i.e. taxes will go up later).  If people recognise that fact, they may instead choose to consume less and save more in anticipation of that future tax bill, therefore lowering the multiplier.  If it gets to a point where there is no difference between raising-taxes-now and borrowing-now-and-raising-taxes-later, we have Ricardian equivalence.
  • If the extra government spending is paid for by borrowing, that will raise interest rates (Interest rates and the price of bonds move in opposite directions – by selling more bonds, the government will be increasing their supply and thus lowering their price; hence, the interest rate will rise).  If the interest rate goes up, that makes it more expensive for private businesses to borrow, which means that private investment will go down.  This is the crowding-out effect.  Since GDP = Consumption + Private Investment + Government spending + Net exports, this will lower the multiplier as well.
  • The size of the multiplier will also depend on the size of the extra government spending.  Generally speaking, the multiplier will be smaller for the second extra dollar spent than for the first and smaller again for the third.  That is, increasing government spending exhibits decreasing marginal returns.  This is because the second and third points listed above will become more and more relevant for larger and larger amounts of extra government spending.
  • Everything gets more complicated when you start to look at current tax rates as well. An alternative to a debt-funded expansion in spending is a debt-funded reduction in revenue (i.e. a tax cut). The multiplier can be very different between those two circumstances.
  • Then we have what is arguably the most important part: where the extra spending (or the tax cut) is directed. Poor people have a much higher marginal propensity to consume than rich people, so if you want to increase government spending, you should target the poor to get a larger multiplier. Alternatively, cutting taxes associated with an increase in a business (e.g. payroll taxes) will lower the cost of that increase and produce a larger multiplier than a tax-cut for work that was already happening anyway.
  • Next, it is important to note that everything above varies depending on where we are in the business cycle.  For example, the crowding-out effect will be strongest (i.e. worst) when the economy is near full employment and be weakest (i.e. less of a problem) when the economy is in recession.
  • Finally, we have the progressivity of the tax system.  This won’t really affect the size of the multiplier directly, but it is important that you think about it. Rich people pay more tax than poor people, not just in absolute levels (which is obvious), but also as a fraction of their income. That means that the burden of paying back the government debt will fall more on the shoulders of the rich, even after you take into account the fact that they earn more.

Much of what you’ll read arguing for or against a stimulus package will fail to take all of those into account.  People are often defending their personal views on the ideal size of government and so tend to pick-and-choose between the various effects in support of their view.