Earlier this week, a United Press International financial story began this way:

"The aging business expansion that has been underway since March 1975 will give way to a modest economic downturn in the latter half of 1979, Prudential Insurance Co. said today in its annual forecast."

When that story was published in our newspaper, the headline over it was. "Business Expanion Over. Forecast Says."

A casual reader skimming through the paper might have concluded that a "downturn" or recession had been forecast. However, readers who took the time to pursue the story learned that Prudential had also said. "Real growth will average 2 percent next year, down from 4 percent in 1978."

Did that mean there would be a downturn only in the sense of slower growth, not minus growth? It wasn't clear to this reader whether the story and headline were saying business expansion had ended, would end, or would merely slow its pace.

To keep their opening paragraphs short, news writers must cram much information into few words. Headline writers work under even more severe space restrictions. In these circumstances, it is difficult to convey an involved message with precision. Readers who skim - as we all do on occasion - risk missing the real thrust of a story.

The prediction that our economy will slow down a little in 1979 is hardly news at this late date. Economists have been telling us for months that our growth rate will be slower in '79. President Carter has explained policies that are deliberately designed to slow things down in an attempt to curb inflation.

I don't understand why each new prediction of a slowdown continues to be regarded as hot news. But if we in the news business fell duty bound to herald the tidings with funereal solemnity each time, I wish we would at least take care to distinguish between minus growth and slower growth.

If we're imprecise in discussing our economy, there's danger we'll talk ourselves into a depression that need not have occurred. So when you use a term like "downturn" on me, please tell me how far down is down: less than hast year's totals, or less that the growth in last year's totals?