But historically, this measurement is virtually meaningless.

In the last 16 presidential elections since 1960, the party with the most popular convention among television viewers won eight times in November. Eight times it lost.

During the first three nights of each convention this summer, Democrats averaged 20.6 million viewers, the Nielsen company said. Republicans averaged 17 million viewers in July. The estimate for Thursday night, which culminated in Vice President Kamala Harris’ acceptance speech, will be announced later Friday.

“The interesting thing about covering politics is that you see clues about what really matters when often it doesn’t,” says veteran journalist Jeff Greenfield, who covered the Democrats for Politico this week.

According to Nielsen, the Democratic National Convention was more popular with viewers in 12 of the last 16 elections. Although the Democrats won eight of those elections, their candidate received the most votes in 10 of them.

The last time a party lost despite having a more popular convention was in 2016, albeit by a narrow margin: Democrat Hillary Clinton beat Donald Trump at their nominating convention by an average of fewer than a million viewers, according to Nielsen. For all his vaunted popularity as a television attraction, Trump missed the ratings twice and is on track for his third.

The final night of a convention, when the candidate delivers his acceptance speech, usually draws the most viewers. Trump’s speech in July, less than a week after an assassination attempt, reached 25.4 million people, and the average would undoubtedly have been higher had his 92-minute speech not lasted past midnight on the East Coast.

Despite the historic election of Barack Obama as the first black president of the United States in 2008, Republican John McCain’s party conventions were watched by an average of more than four million viewers each evening.

Four times in a row, from 1976 to 1988, the party with the most-watched convention lost the election. These included two clear victories by Republican Ronald Reagan—although a battle for the nomination between Jimmy Carter and Ted Kennedy in 1980 and the nomination of Geraldine Ferraro in 1984 as the first woman on a national ballot likely increased the number of Democrats at the conventions in those years.

People are usually more likely to watch their own party’s convention, Greenfield says. That’s reflected in the ratings this year: Fox News Channel, which appeals to Republicans, had far more viewers at the Republican convention than any other network, while left-leaning MSNBC dominated last week.

It will also be interesting to see whether Harris has been buoyed by her star power – or potential star power. Rumors of a surprise appearance by Beyoncé or Taylor Swift, which were ultimately unfounded, hovered over the Democratic caucus.

Both conventions are as much elaborately staged television events as they are political rallies, and Greenfield said it was clear that Democrats had the upper hand.

“I think if you just look at entertainment value,” he said, “Oprah Winfrey and Stevie Wonder trump Kid Rock and Hulk Hogan.”

David Bauder writes about media for AP. Follow him at http://twitter.com/dbauder.