Last week’s column ascribing recent stock market volatility to more than just a slowing Chinese economy prompted a number of reader questions about China and how the strength of its economy could deteriorate so rapidly.

The Chinese economy actually didn’t begin its slowing all at once. It has been slowing since 2010, but you would never know that by a superficial look at the country’s reported gross domestic product figures. It’s a great lesson in the importance of not making investment decisions based solely on headline news.

We were warned. China Premier Li Keqiang has repeatedly said that GDP is easily manipulated and should not be used to gauge a country’s true economic health. Investors should have taken his advice.

The four broad components of GDP are personal consumption, capital investment, government expenditures and net exports. While China’s GDP has averaged an annual increase of 15.8 percent since 2010, the consumer and export components have been in relative decline. The percent of GDP contributed by consumer expenditures dropped from 46 percent to 37 percent. Annual export growth fell from 26 percent in 2011 to a net decline by 2014.

But the Chinese government has been able to manipulate its GDP by making increasingly massive capital investments, financed by government dollars.

Since 2010, China has added 63 billion (with a B) square feet of new commercial office space, or about five times the total amount of office space in Manhattan. A substantial but unreported amount of that sits empty.

Residential real estate is similarly overbuilt. Speculators, buoyed by zero-down mortgages, have built and purchased so many spec houses that 22 percent of the housing stock sits empty.

The Chinese government money used to build these projects boosted the GDP, but did so without any accompanying significant increase in wealth, productivity or even population.

Rather than trust GDP, Keqiang has instead suggested that a country’s economic health can be measured by its electricity production, rail traffic and new bank loans — a formula that would have revealed an economy that has been slowing for five years. Since 2010, growth in electricity production and bank loans has fallen to zero, while rail traffic is actually declining at a 10 percent annual rate. And these declines have occurred while the country’s GDP has continued to increase at a torrent pace.

It’s not likely that you are going to dissect the components of China’s or any country’s GDP before making decisions about your 401(k) or IRA. That’s OK. But if you are about to make some significant change in your investments or their allocation based solely on the lead story on NBC News, stop and consider whether it passes the smell test. If something seems illogical, there’s a good chance it fails.