The United Kingdom is in the midst of a massive social experiment. The country’s large employers had until last week to publish data for the first time on their gender wage gaps, including the difference between male and female employees in base compensation and bonuses, as well as the gap in each pay quartile. The dataset is in no ways perfect. But it has revealed how far we have to go in fixing pay inequities on both sides of the Atlantic.

The UK’s requirement is one of the first countrywide attempts at using public transparency and accountability as a bludgeon against the stubborn gender wage gap. So far the effort has revealed that 78 percent of companies pay men more than women, and that that women make less in every single sector. Some of the gaps are staggering: Ryanair, the discount airline, pays men about 72 percent more, for example.

Researchers seeking answers to why pay gaps persist may be frustrated. “If the information is just at the level of a company and not split by job category,” said Amalia Miller, economics professor at the University of Virginia, “then it is a bit hard to interpret where pay differences come from.” Nor, Harvard economist Claudia Goldin pointed out in an email to me, do these numbers include other factors that generally impact how much people are paid, such as workers’ levels of education, experience, or the hours they work.

Some companies don’t seem to be handing over accurate data, either. With days to go until the deadline, some simply entered zeroes in every field, while others reported mathematically impossible numbers or removed certain employees from the calculations. Another 1,500 missed the deadline completely.

But obvious trends still emerge from the imperfect dataset. For example, women appear to do worse in high-wage sectors because there is such a wide distribution of pay: some people making top dollar, others making very little. Pay in low-wage sectors, on the other hand, is clustered close together at the bottom for everyone. So gender wage gaps will be bigger in high-wage industries, even if “in absolute terms [women] do much better than in the low wage sector,” Goldin said. “This is something we already knew, but it is nice to see it play out in these data.”