ON JANUARY 19th China declared that its gross domestic product had grown by 6.9% in 2015, accounting for inflation—the slowest rate in a quarter of a century. It was neatly within the government’s target of “around 7%”, but many economists wondered whether the figure was accurate. Online chatter in China about dodgy GDP numbers was fuelled a week later by the arrest of the man who had announced the data: Wang Baoan, the head of the National Bureau of Statistics. The country’s anti-graft agency accused him of “serious disciplinary violations”, a euphemism for corruption. But beyond all the (justifiable) doubts about the figures lies another important question. That is: why does China have a GDP target at all?

It is the only large industrial country that sets one. Normally central banks declare specific goals for things like inflation or unemployment. The idea that a government should aim for a particular rate of output expansion, and steer the economy to achieve that, is unusual. In the case of China, which is trying to wean its economy off excessive reliance on GDP-boosting (but often wasteful and debt-fuelling) investment, it is risky. It is inconsistent with the government’s own oft-repeated mantra that it is the quality of growth that matters, not the quantity.

In the past, setting a target may not have made much difference. For all but three of the years between 1992 and 2015, China’s growth was above target, often by a big margin. A rare period when targets seemed to affect the way officials tried to manage the economy was from 2008 to 2009, when growth fell sharply (see chart). It would be hard to argue that targets themselves have been responsible for China’s overall (impressive) record of growth in recent decades.

Now, however, the economy is slowing. This is inevitable: double-digit growth is no longer achievable except at dangerous cost (total debt was nearly 250% of GDP in the third quarter of 2015). But the government is worried that the economy may slow too fast, and that this could cause a destabilising surge in unemployment. So it has been ramping up investment again, and goading local governments to do the same by setting a high growth target. For a while there were signs that the leadership itself had doubts about the merits of GDP target-setting. In 2013 Xinhua, an official news agency, decried what it called the country’s “GDP obsession”. By the next year, 70 or so counties and cities had scrapped their targets. In 2015 Shanghai joined them, becoming the first big city to break with orthodoxy (each level of government sets its own GDP target, often higher than the national one). Liu Qiao of the Guanghua School of Management at Peking University says the central government ought to follow suit. Last year there were hints that it might. The prime minister, Li Keqiang, said the government would not “defend [the target for 2015] to the death”. And in October, talking about the government’s work on a new five-year economic plan (which will run from 2016 to 2020), President Xi Jinping avoided mentioning a number. That raised expectations that targets might at least be downplayed, if not abandoned. They have not been, however. An outline of the five-year plan, unveiled in November, contained the usual emphasis on growth. And Mr Xi appeared to change his tune, saying expansion must average at least 6.5% a year until 2020. Many economists believe that will require yet more debt-inducing stimulus. A GDP target for this year is all but certain to be announced, as usual, at the annual session of the legislature in March (when the five-year plan will also be adopted). It will probably be higher than 6%. Speculation that the government might set a target range in order to give itself more policymaking flexibility (as the IMF and the World Bank have urged) has ebbed. In December some national legislators complained that local governments were busting their debt ceilings because there was “still too much emphasis on GDP”.

So why is there still a target? The reasons are political. In a country so large, central leaders are always fearful of losing their grip on far-flung bureaucrats: setting GDP targets is one means by which they believe they can evaluate and control those lower down. Local officials are also judged by environmental standards, social policies and what the Communist Party calls “virtue”—that is, being uncorrupt and in tune with the party’s latest interpretation of Marxist doctrine. But GDP is usually the most important criterion, having the attraction of being (roughly) measurable.

A study in 2013 by Deng Yongheng of Singapore National University and Wu Jing of Tsinghua University in Beijing looked at the careers of officials who had worked as mayors in 283 cities. It found that those who presided over higher growth rates in their cities, relative to the rates notched up by their predecessors, had got better jobs afterwards. Since the study was conducted, there has been little sign of any change in this pattern.

Depressingly, the academics found that the more the mayors had increased investment in environmental protection, the lower their likelihood of being promoted had turned out to be. The government finds environmental targets more difficult to set than growth ones. The environment ministry is trying to create a measure of “green GDP” (roughly, output minus the cost of environmental damage) that could be used to assess the performance of local officials. But it had a stab at this before, in 2004, and got nowhere: the damage proved too tricky to calculate.