(NBBJ) - The prediction that millennials would overtake baby boomers as key consumers of wine has been fermenting for several years, but the debate on whether that time has come is bubbling over amid conflicting reports.

Rob McMillan, founder of Silicon Valley Bank’s Silicon Valley-based Premium Wine Division, on Jan. 21 reported millennials (ages 21–37) made up 16 percent of consumers of fine wine — retailing for more than $20 a bottle — compared with 41 percent for baby boomers (50–67), 32 percent for generation X (38–49), and 11 percent for matures (68-plus).

But four days later at its Consumer Research Conference in New York, Wine Market Council presented results from its June consumer-segmentation study, suggesting consumption by millennials increased about 13 percent from 2014, overtaking boomers with 159.6 million cases of still and sparkling wine, or 42 percent of the total, compared with the boomers’ 114.1 million cases, or 30 percent. Per-capita consumption was 3.1 glasses for millennials and 1.9 for boomers.

Then for the conference in Yountville on Feb. 8, the council presented revised high-frequency consumption proportions, 38 percent for boomers and 30 percent for millennials, and per-capita consumption figures to 2.4 glasses for millennials and 2.0 for boomers.

McMillan took to his “SVB on Wine” blog on March 22 to dispute the figures for millennials and question the methodology.

“The only reason I am bringing this up now is the information put out in N.Y. by the WMC was way outside of any other research, and I started running into wineries using the information to strategize and using bad information would hurt their chances for success and cost them money,” McMillan wrote to a commenter on the post.

The Wine Market Council issued a statement March 24 to clarify five points in its results.

“At our Yountville conference in March we made a correction to the data that was originally presented at our New York presentation in January,” said John Gillespie, council president, in the statement. “In the New York City presentation, an error was made, which resulted in an inaccurate projection of wine consumption volumes by generation.” The error was caused by using data from the council’s annual consumer-tracking study of “high-frequency” wine drinkers instead of the group’s annual consumer-segmentation study.

“The overstatement of glasses per occasion, once corrected, leaves us with the conclusion that while baby boomers remain the largest wine consuming generation, millennials are rapidly closing that gap,” Gillespie said. The Wine Market Council stood by these points:

U.S. millennial adults top baby boomers, 79 million vs. 75 million.