Among the “everyone knows” factoids in marketing, it’s accepted pretty much without question that women are the purchasing decision-makers in households far more than men. Whether it’s decisions on consumer spending or healthcare services … women are much more likely to be making those decisions compared to men.

And the figure commonly cited? Women are responsible for ~80% of the decisions. But how accurate is this … or is it time to reconsider this notion?

A survey conducted last year of ~4,000 Americans age 16 and older by The Futures Company, a London-based marketing consulting firm, found that ~37% of women claimed they have primary responsibility for shopping decisions in their household, while ~85% claimed they have primary or shared responsibility.

And the figures for the male respondents in this survey? Substantially the same, it turns out: 31% claimed they have primary shopping responsibility and 84% claimed that the responsibility is shared.

Emily Parenti, marketing director at Futures, concluded that the survey results “tell a different story” than the common perception of how much women control the purse-strings in households.

Indeed, the Futures survey is one of the first ones that actually goes so far as to quantify the issue. Ira Mayer, president of EPM Communications which publishes the newsletter Marketing to Women, has attempted to find the origin of the accepted 80% figure – but has come up empty.

“There is never any sourcing of the number,” Mayer says. And yet, “it’s become accepted folklore.”

When challenged to cite corroboration, students of marketing point to the book Marketing to Women, published in 2002 by Marti Barletta, wherein the claim is made that women “handle 80% to 90% of spending and purchasing for the household.”

And yet … Barletta has never been able to cite the source for this claim, either. Instead, she considers it “one of those rules-of-thumb numbers that everyone in the industry uses.”

Perhaps marketers need to take a look at this rule-of-thumb again. Because in addition to the Futures survey, a 2008 online research survey conducted by Boston Consulting Group asked women and men to estimate what percentage of household spending they influence or control.

True to form, the average answer given by women in the BCG survey was 73%. But the average answer given by men was 61%.

So in essence, both genders are claiming responsibility for a controlling or influence more than 50% of the spending in their household.

This points to a difference in perspective that likely won’t be going away anytime soon. Indeed, Marti Barletta still claims to be “pretty comfortable” with the 80% figure for female control over household spending. “Even being conservative, I wouldn’t go below 75%,” she asserts.

Whatever the correct figure actually is, one thing we can be certain of is that the notion of women having overwhelming control of household spending is off-base. And so, consumer product manufacturers would be wise to recalibrate their thinking as they engage in their product development and marketing activities and programs.