This week, half of the Major League Baseball (MLB) franchises celebrated their Opening Days, marking the first day of baseball season.

Opening Day attendance can tell us a lot of things. For example, attendance at the Washington Nationals’ home opener was up 11% this year, due to high hopes for the team this season.

But can it also tell us about the economy? Last year, analysts from the technology firm ConvergEx claimed that baseball attendance serves as a good indicator of consumer confidence.

Baseball, they said, has a broad fan base, both geographically and socioeconomically. Also, as Nick Colas, a strategist at ConvergEx, told Bloomberg last year, tickets are “sufficiently expensive that the people who want to go to the ball game will actually take the time to think about how many games they want to go to, and as a result, attendance becomes rather cyclical.”

To illustrate this, they showed that baseball attendance slowly declined since 2007. However, in the last two years, attendance has picked up 0.7 percent in the 2010 season and 1.8 percent in the 2011 season, which CNBC suggested might be a sign that consumer confidence was growing.

So, how does this year look? Below is a table of opening day attendance, as compared to last year, for the 15 teams that have had home openers this week:

(Source: www.sportsnetwork.com)

On average, attendance on opening day fell by 2 percent, compared to last year.  Notable exceptions include the Washington Nationals, whose attendance surged 11 percent to a record-high for Opening Day, and the Oakland A’s, who set an American League record on Monday for most consecutive Opening Day losses. These exceptions aside, what’s surprising is that this trend seems to hold across different market sizes. Medium-market teams, like the Houston Astros, and small-market teams, like the Pittsburgh Pirates, all failed to pick up more attendance this year.

This data does seem consistent with consumer confidence data: the Conference Board’s consumer confidence index was 59.7 this March, compared to 70.2 in March 2012.

Of course, this sort of estimation is a bit like the Big Mac Index: interesting to ponder, but certainly not bulletproof. A few reasons to be skeptical about the data include, but are not limited to, the following:

1. Lack of non-economic factors: the growing popularity of the NFL and changing demographics may have also eroded MLB attendance over time.
2. Incomplete data: Only 15 of the 30 MLB franchises have held their home openers this week; the rest are scheduled for tonight and next week. Also, using attendance for the entire season, rather than just for Opening Day, would be a more consistent measure.

Nevertheless, as we welcome in a new season, it’s an interesting point to think about as you take your seats in crowded—or not so crowded—baseball stadiums this summer.