By Chris Adams

International trade is constantly in the headlines, and the data that underpin it is as well.

But given the unfortunate reality that journalists aren’t well known for their math skills, some of the basic data that help economists, business executives and regulators document global trading patterns are often mangled in trade coverage.

“It is an area where there is a lot of misunderstanding,” said Jeffrey Timmermans, a professor of journalism at the University of Hong Kong.

In a session with National Press Foundation fellows, Timmermans opened with a quiz, listing 10 countries, most of them developing, from Asia and Latin America. And he asked, “What do they all have in common?”

“All 10 countries supply clothing to U.S. discount clothing retailer Old Navy,” he said. For kicks, Timmermans will go into Old Navy outlets and check the “Made in …” tags on its clothing.

“Even in the same stack of T-shirts, the same style of clothing, you’ll have several counties represented,” Timmermans said. “It’s a phenomenal example of the global supply chain.”

Timmermans (bio, Twitter), who before his academic work had a long career at The Wall Street Journal, detailed for fellows how to best read the world’s trade numbers.

It’s also important for journalists to know how to interpret those numbers. Take a nation’s trade deficit: A bad thing? The United States, for example, has a pretty big one – at least in merchandise, or the trading of goods. But trade with services – tourism, intellectual property, finance – are a surplus for the U.S.

Timmermans led fellows through readily available statistics on trade, showing them both where to find them and how to use them. Numbers from the United States tend to be pretty accessible and trustworthy; those from some other countries aren’t as readily available or their origins are a bit murky.

He also described what he called the most important measure of a country’s financial status: the balance of payments statement, which records a country’s cross-border transactions – both current account transactions (including trade in goods and services) and capital transactions.