As a foreigner in China, you get used to hearing the retort “You don’t know China!” spat at you by locals. It’s usually a knee-jerk reaction to some uncomfortable modern issue or in defense of one of the many historical myths children in the mainland are taught as unshakeable facts about the world. But it’s also true. We don’t know China. Nor, however, do the Chinese — not even the government.

We don’t know China because, in ways that have generally not been acknowledged, virtually every piece of information issued from or about the country is unreliable, partial, or distorted. The sheer scale of the country, mixed with a regime of ever-growing censorship and a pervasive paranoia about sharing information, has crippled our ability to know China. Official data is repeatedly smoothed for both propaganda purposes and individual career ambitions. That goes as much for Chinese as it does for foreigners; access may sometimes be easier for Chinese citizens, but the costs of going after information can be even higher.

We don’t know the real figures for GDP growth, for example. GDP growth has long been one of the main criteria used to judge officials’ careers — as a result, the relevant data is warped at every level, since the folk reporting it are the same ones benefitting from it being high. If you add up the GDP figures issued by the provinces, the sum is 10 percent higher than the figure ultimately issued by the national government, which in itself is tweaked to hit politicized targets. Provincial governments have increasingly admitted to this in recent years, but the fakery has been going on for decades. We don’t know the extent of bad loans, routinely concealed by banks. We don’t know the makeup of most Chinese financial assets. Sometimes we don’t know the good news of recoveries because the concealment of bad news beforehand has disguised it. We don’t know China’s real Gini coefficient, the measure of economic inequality.

But economic data may be, ironically, more reliable than most just because so much attention has been paid to its unreliability. China’s National Bureau of Statistics itself has repeatedly called out instances of bad data reportage and now attempts to gather provincial data directly itself. There have been clean-ups and attempts at rectifying past mistakes — although the increasingly ideological and paranoid turn of the party-state may be obstructing these efforts.

But what we don’t know goes far beyond just economics. Look at any sector in China and you’ll find distorted or unreported public information; go to the relevant authorities and they’ll generally admit the most shocking practices in private.

We don’t know the true size of the Chinese population because of the reluctance to register unapproved second children or for the family planning bureau to report that they’d failed to control births. We don’t know where those people are; rural counties are incentivized to overreport population to receive more benefits from higher levels of government, while city districts report lower figures to hit population control targets. Beijing’s official population is 21.7 million; it may really be as high as 30 or 35 million. Tens — perhaps hundreds — of millions of migrants are officially in the countryside but really in the cities. (Perhaps. We don’t know the extent of the recent winter expulsions of the poor from the metropolises.) We don’t know whether these people are breathing clean air or drinking clean water because the environmental data is full of holes.

We don’t know anything about high-level Chinese politics. At best, we can make — as I have — informed guesses. We don’t know how the internal politics of Zhongnanhai, the Chinese Kremlin equivalent, operate. Chinese politicians don’t write tell-all memoirs; Chinese journalists can’t write a Fire and Fury, a What It Takes, or even a Game Change. We don’t know whether Xi Jinping truly values China’s wealth and power or only his own.

We don’t know whether the officials targeted in the “anti-corruption” campaigns were really unusually corrupt, lascivious, or treacherous — or whether they were just political opponents of Xi. We don’t know the extent of factionalism within the Chinese Communist Party, though we do know how often its existence is condemned — by Xi and his faction. We don’t know whether officials who lather slavish praise on Xi actually believe anything of what they say or are acting out purely out of fear and greed.

We don’t know what people really think. We don’t know whether interviewees really support the government or give cautious answers when asked questions by a stranger in a politically repressive country. We don’t know why Chinese tell pollsters they are more trusting of others than any other country in the world, while in practice paranoia about the intentions of others is so rampant that old people aren’t helped on the streets for fear they’re running a scam and children like toddler Wang Yue are left to die after being hit by cars.

We don’t know the real defense budget. We don’t know the everyday conditions of the Chinese army because the restrictions placed on military coverage and the ability of soldiers to talk are even more tightly limited than for civilians.

We don’t know how good Chinese schools really are because the much-quoted statistics provided by the Program for International Student Assessment (PISA) that placed China first in the world were taken from the study of a small group of elite Shanghai schools. As soon as that was expanded merely to Beijing — another metropolis — and two rich provinces, the results dropped sharply. (PISA’s willingness to accept only this limited sample is typical of the gullibility and compliance of many foreign NGOs, especially in education, when dealing with China; I have seen numerous foreign educators fall victim to obvious Potemkinism, including believing that Beijing No. 4 High School — the rough equivalent of Eton — was a “typical Chinese public school.”) We don’t know the extent of the collapse of rural education. We don’t know the real literacy figures, not least because rural and urban literacy is measured by different standards — a common trick for many figures.

We don’t know the real crime figures, especially in the cities, which may represent as little as 2.5 percent of the actual total. We don’t know the death toll for the ethnic Uighur insurgency in Xinjiang, where local officials, in the words of one government terrorism expert, “bend figures as much as during the Great Leap Forward,” nor do we know how many people are currently held in “re-education camps.” (Incidentally, we don’t know how many people died in the Great Leap Forward, piled up in village ditches or abandoned on empty grasslands: the 16.5 million once given in official tolls or the 45 million estimated by some historians.)

And we don’t know what we don’t know. These are the known unknowns, but the unknown unknowns are equally worrying. We may be missing the biggest future stories, the ones that will shake or transform China and the world, right now. Foreign reporters are limited to residence in a few major cities, chiefly Beijing, Shanghai, and Shenzhen; they are followed and harassed when they travel elsewhere in the country and find it particularly difficult to reach the countryside. (According to the official population figures, Beijing and Shanghai, often portrayed as the norm for the new China, house less than 4 percent of the country’s residents.) The situation for Chinese journalists is far worse; a limited ability to conduct investigative journalism in the 2000s has been almost obliterated by authorities determined that there will be no oversight beyond the party. Fear grips throats; those who would once give names now talk anonymously, where many others do not talk at all.

Our sources of information, always a thin stream, have dried up almost entirely under an increasingly tight censorship regime of the last few years. Social media platform Weibo was once a limited window into provincial complaints and scandals; it is now massively censored. Private messaging groups on WeChat, an all-conquering messaging service, replaced it; last year, they were massively censored in turn.

All this makes the work of those who manage to successfully extract meaningful economic or political data, such as the masterful researcher Adrian Zenz, all the more impressive. And as the government closes down any source of information outside its control, we can only wonder at how much it knows itself. Local officials have always demanded enormous amounts of data — it’s not uncommon to receive requests like: “List everybody who attends religious services in your district and where.” But the system has always distorted the information it sends up even internally and may be doing so even more as Xi establishes outright dictatorship. Li Keqiang, the increasingly irrelevant (we think) Chinese premier, complained to U.S. diplomats in 2007 of his inability to know basic economic information about the province he then ruled and his need to send out friends and colleagues on surreptitious data-gathering trips.

The government’s solution to this is an increasing faith in big data, a belief that by circumventing lower-level officials it can gather information directly from the source. Huge amounts of money are being poured into big data, including efforts at predictive policing and the widespread monitoring of dissidents. The government requires Chinese firms, and foreign firms with a Chinese presence, such as Apple, to store and hand over data on a vast scale. But big data itself is prone to systematic distortions, misplaced trust, and the oldest rule of coding: garbage in, garbage out.

As the economist Josiah Stamp recounted of another power trying to control a vast territory through oppressive means, “The Government [of British India] are very keen on amassing statistics—they collect them, add them, raise them to the nth power, take the cube root and prepare wonderful diagrams. But you must never forget that every one of these figures comes in the first instance from the chowty dar (village watchman), who just puts down what he damn pleases.” Will technology let the Chinese government today do any better? We don’t know.