Wage stagnation in the US: more than meets the eye

If you can, always look below the surface of data.

Via the Economist journalist Daniel Knowles comes a good example of why its important to look below the surface of statistics. American economist Steve Landsburg addresses a commonly heard refrain – that the wage of the median worker has barely risen in the past thirty years – and shows that all is not as it seems.

Landsburg cites a book by economist Edward Conard (first chapter, containing what we're talking about, here), which itself cites the Census Bureau. I confess that, without a more specific citation, I can't find the exact data Conard uses, but have found similar enough data (pdf, table A-5) to confirm the overall thrust of the argument.

Conard shows that from 1980 to 2005, median income in the US rose just 3 per cent once inflation is taken into account, from $25,000 to $25,700. 2005 is pre-crash, as well, so this isn't a tale of the recession.

But when you break the data down by race and gender, a very different story appears:

  1980 Median 2005 Median Increase
All Workers 25,000 25,700 3%
White Men 30,700 35,200 15%
Nonwhite Men 19,300 22,300 16%
White Women 11,200 19,600 75%
Nonwhite Women 10,200 16,500 62%

For every single demographic group, there was a much bigger increase in the median wage than we see when the groups are combined. The reason for this is obvious when it's pointed out: demographic change in the US means that there are far more (low-salaried) women and people of colour working now than there were in 2005, which pushes the overall average down.

Landsburg illustrates it with a farmyard analogy:

Imagine a farmer with a few 100-pound goats and a bunch of 1000-pound cows. His median animal weighs 1000 pounds. A few years later, he’s acquired a whole lot more goats, all of which have grown to 200 pounds, while his cows have all grown to 2000. Now his median animal weighs 200 pounds.

A very silly person could point out to this farmer that his median animal seems to be a lot scrawnier these days. The farmer might well reply that both his goats and his cows seem to be doing just fine, at least relative to where they were.

This is almost an example of Simpson's Paradox, a well-known (to stats nerds) effect where the direction of a correlation disappears when that correlation is disaggregated. I was taught it with an example involving racial discrepancies in application of the death penalty:

Sixty per cent of white murderers are executed for their crimes, and fifty per cent of black murderers. Are black people discriminated against in the application of the death penalty?

Now suppose that we break down the murder victims by race as well. We find the common pattern that people tend to attack victims of their own race:

Number of murders where death penalty is applied

White Murderer Black Murderer
White Victim 50/70=71% 25/30=83%
Black Victim 10/30=33% 25/70=36%

What about now? Does it begin to look like black people are discriminated against? In this example, black people are more likely to be executed for the murder of black or white victims; but because the murder of black victims isn't taken as seriously by the courts, the fact that murderers predominantly attack people of their race makes it look like black people are less likely to be executed than white people.

The median income example isn't quite a case of Simpson's Paradox, because there is still a positive increase in wage whether or not the statistics are disaggregated. But it's still an example of a time when it is best to dig beneath the surface.

But there is more to be said on the story of wage stagnation. Because a second claim normally accompanies the belief that US wages have stagnated, and that is that there has been a "decoupling" of wages. Due to rising inequality, the median household wage hasn't risen as fast as the mean wage:

If we've seen that the median wage grows faster when disaggregated, then the solid red line is likely to take a steeper ascent. But what happens to the dashed red line when disaggregated?

Sadly, I cannot find the data required to answer the question. If anyone knows where to look, tell me, and maybe we can put the issue to rest.

An immigrant worker protests in Orlando, Florida. Photograph: Getty Images

Alex Hern is a technology reporter for the Guardian. He was formerly staff writer at the New Statesman. You should follow Alex on Twitter.

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Like it or hate it, it doesn't matter: Brexit is happening, and we've got to make a success of it

It's time to stop complaining and start campaigning, says Stella Creasy.

A shortage of Marmite, arguments over exporting jam and angry Belgians. And that’s just this month.  As the Canadian trade deal stalls, and the government decides which cottage industry its will pick next as saviour for the nation, the British people are still no clearer getting an answer to what Brexit actually means. And they are also no clearer as to how they can have a say in how that question is answered.

To date there have been three stages to Brexit. The first was ideological: an ever-rising euroscepticism, rooted in a feeling that the costs the compromises working with others require were not comparable to the benefits. It oozed out, almost unnoticed, from its dormant home deep in the Labour left and the Tory right, stoked by Ukip to devastating effect.

The second stage was the campaign of that referendum itself: a focus on immigration over-riding a wider debate about free trade, and underpinned by the tempting and vague claim that, in an unstable, unfair world, control could be taken back. With any deal dependent on the agreement of twenty eight other countries, it has already proved a hollow victory.

For the last few months, these consequences of these two stages have dominated discussion, generating heat, but not light about what happens next. Neither has anything helped to bring back together those who feel their lives are increasingly at the mercy of a political and economic elite and those who fear Britain is retreating from being a world leader to a back water.

Little wonder the analogy most commonly and easily reached for by commentators has been that of a divorce. They speculate our coming separation from our EU partners is going to be messy, combative and rancorous. Trash talk from some - including those in charge of negotiating -  further feeds this perception. That’s why it is time for all sides to push onto Brexit part three: the practical stage. How and when is it actually going to happen?

A more constructive framework to use than marriage is one of a changing business, rather than a changing relationship. Whatever the solid economic benefits of EU membership, the British people decided the social and democratic costs had become too great. So now we must adapt.

Brexit should be as much about innovating in what we make and create as it is about seeking to renew our trading deals with the world. New products must be sought alongside new markets. This doesn’t have to mean cutting corners or cutting jobs, but it does mean being prepared to learn new skills and invest in helping those in industries that are struggling to make this leap to move on. The UK has an incredible and varied set of services and products to offer the world, but will need to focus on what we do well and uniquely here to thrive. This is easier said than done, but can also offer hope. Specialising and skilling up also means we can resist those who want us to jettison hard-won environmental and social protections as an alternative. 

Most accept such a transition will take time. But what is contested is that it will require openness. However, handing the public a done deal - however well mediated - will do little to address the division within our country. Ensuring the best deal in a way that can garner the public support it needs to work requires strong feedback channels. That is why transparency about the government's plans for Brexit is so important. Of course, a balance needs to be struck with the need to protect negotiating positions, but scrutiny by parliament- and by extension the public- will be vital. With so many differing factors at stake and choices to be made, MPs have to be able and willing to bring their constituents into the discussion not just about what Brexit actually entails, but also what kind of country Britain will be during and after the result - and their role in making it happen. 

Those who want to claim the engagement of parliament and the public undermines the referendum result are still in stages one and two of this debate, looking for someone to blame for past injustices, not building a better future for all. Our Marmite may be safe for the moment, but Brexit can’t remain a love it or hate it phenomenon. It’s time for everyone to get practical.