I’ve previously blogged on my belief that the massive rise in youth is due to Labour’s decision in 2008 to abolish for the .

has gone better than mere belief, and analysed the relationship between overall unemployment and youth unemployment.

The graph has (thanks Stephen Hickson!) the unemployment rate for those aged 15-19 and the unemployment rate for everyone else (aged 19 and up). It looks to me like the proper relationship is a combination of a level shift and a multiplicative effect. When the adult rate is very low – below four percent or so – the youth rate bounces around at a point about 10 to 12 points higher than the adult rate. When the adult rate is high, the youth rate exceeds that constant by a multiple of the adult rate. …

Both the constant and the adult rate come up highly significant. So, over the period 1986 to present, we can expect the youth rate to be 1.44 times the adult rate (the multiplicative effect – about 44% above the adult rate) plus a constant of 9 percentage points. So if the adult rate is 5, the youth rate should be 16.2. We’ve ruled out the “it’s just ratios” argument – there is a constant term in there; we’ve also ruled out that it’s just a level shift because the coefficient is significantly greater than 1.

So Eric has calculated the best fit of the data is that the youth unemployment rate will 9% higher than 1.44 times the adult unemployment rate.

He then plots the “residuals”, which is how much greater or smaller the youth unemployment rate has been, compared to what the formula predicts.

So that formula looks pretty good up until, umm well 2008. Eric continues:

If we look at the top graph, we see youth unemployment rates went up a lot during the recession of the early 1990s. But over that period, youth unemployment rates were never more than a couple of points above what the very simple model predicted (residuals graph, above). In recessions, it does look like the youth rate gets hit harder than the adult rate. But look at what happens starting around fourth quarter 2008. We now have residuals that blow up the model. Something really weird starts happening to the youth unemployment rate at the end of 2008. Youth unemployment is now about 10 points higher than we’d expect using the simple model.

And if one goes for different formulas:

I tried a few different variations allowing the constant and the slope to shift for high and for low levels of adult unemployment.  But none of that made any substantial difference.

So the conclusion:

The econometrics here are very simplistic and do nothing to account for differences in labour force participation rates or the obvious problem of serial correlation in the time series data.  But the simple model is still pretty telling.  If we allow youth unemployment rates to vary both as a level shift above the adult rate and as a multiple of the adult rate, which is what we’re doing when we run the simple regression with a constant term, we still have a jump in the current youth unemployment rate that is well above that seen in prior recessions.

My first cut explanation remains the abolition of the youth minimum wage.

Now this does not prove beyond doubt it was the abolition of youth rates that pushed youth unemployment up an extra 10%. But it is the most likely explanation.

The challenge for those who think abolishing youth rates did not contribute to the increase in youth unemployment, is to put up their own data and credible explanations to explain the massive gap between youth and adult unemployment.