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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Why Theresa May can't end speculation of an early general election

Both Conservative and Labour MPs regard a contest next year as the solution to their problems. 

One of Theresa May’s first acts as a Conservative leadership candidate was to rule out an early general election. After a tumultuous 2015 contest and the EU referendum, her view was that the country required a period of stability (a view shared by voters). Many newly-elected Tory MPs, fearful of a Brexit-inspired Ukip or Liberal Democrat surge, supported her on this condition.

After entering Downing Street, May reaffirmed her stance. “The Prime Minister could not have been clearer,” a senior source told me. “There won’t be an early election.” Maintaining this pledge is an important part of May’s straight-talking image.

But though No.10 has wisely avoided publicly contemplating an election (unlike Gordon Brown), the question refuses to die. The Conservatives have a majority of just 12 - the smallest of any single-party government since 1974 - and, as David Cameron found, legislative defeats almost inevitably follow. May’s vow to lift the ban on new grammar schools looks to many like an unachievable task. Former education secretary Nicky Morgan and former business minister Anna Soubry are among the Tories leading the charge against the measure (which did not feature in the 2015 Conservative manifesto).  

To this problem, an early election appears to be the solution. The Tories retain a substantial opinion poll lead over Labour, the most divided opposition in recent history. An election victory would give May the mandate for new policies that she presently lacks.

“I don’t believe Theresa May wishes to hold an early election which there is evidence that the country doesn’t want and which, given the current state of the Labour Party, might be seen as opportunistic,” Nigel Lawson told today’s Times“If, however, the government were to find that it couldn’t get its legislation through the House of Commons, then a wholly new situation would arise.”

It is not only Conservatives who are keeping the possibility of an early election alive. Many Labour MPs are pleading for one in the belief that it would end Jeremy Corbyn’s leadership. An early contest would also pre-empt the boundary changes planned in 2018, which are forecast to cost the party 23 seats.

For Corbyn, the possibility of an election is a vital means of disciplining MPs. Allies also hope that the failed revolt against his leadership, which Labour members blame for the party’s unpopularity, would allow him to remain leader even if defeated.

Unlike her predecessors, May faces the obstacle of the Fixed-Term Parliaments Act (under which the next election will be on 7 May 2020). Yet it is not an insurmountable one. The legislation can be suspended with the backing of two-thirds of MPs, or through a vote of no confidence in the government. Alternatively, the act could simply be repealed or amended. Labour and the Liberal Democrats, who have demanded an early election, would struggle to resist May if she called their bluff.

To many, it simply looks like an offer too good to refuse. Which is why, however hard May swats this fly, it will keep coming back. 

George Eaton is political editor of the New Statesman.