Ten minutes into listening to our boss talk about the turning radius of his new riding mower, a colleague leaned over and whispered, "Do you think any meeting ever starts on time?" 

We decided to test his theory, logging the start time of every meeting we attended. (Since the average meeting started seven minutes late, we had plenty of time to collect that data.)

What did we find? Out of nearly 700 meetings, only three -- yep, three -- actually began on time. 

Which means those were the only three meetings that were as effective as they could have been. According to a 2018 study published in Journal of Organizational Behavior, meetings that start late aren't just a waste of time and a cause for irritation.

Meetings that start late also turn out to be much less productive. As the researchers write:

We found significant differences concerning participants' perceived meeting satisfaction and meeting effectiveness, as well as objective group performance outcomes (number, quality, and feasibility of ideas produced in the meeting).

We also identified differences in negative socio-emotional group interaction behaviors depending on meeting lateness.

In real terms, that means a meeting that started 10 minutes late was a third less effective -- in terms of outcomes, both actual and perceived -- than a meeting that started on time. A third as many ideas were generated. The feasibility of ideas generated was nearly a third lower.

And then there are the "socio-emotional group interaction behaviors."

Take the average meeting. A few people arrive early, whether physically or virtually. They start chatting. The "room" fills. It's time to start, but a few people still haven't arrived. Or one or two key people -- usually the ones in charge of the meeting -- keep chatting. Time drags.

Eventually, someone says, "OK, we'd better get started."

In the meantime, much of the focus and enthusiasm has been sucked from the room, and no matter how hard you try -- whether leader or participant -- that focus and enthusiasm is extremely hard to recapture.

Keep in mind those effects occurred even when certain meetings actually did start on time; if your employees assume meetings will always start late, that assumption still affects their performance and participation. 

The solution is simple. Start your meetings on time; no excuses. Arriving late is rude. Arriving late implies your time is more valuable than that of other people. And if you need a bottom-line reason, arriving late compromises the outcome of a meeting you felt was important enough to hold in the first place. 

Sum it all up, and arriving late is like saying, "This meeting is important, but, hey, it's not that important."

Granted, always starting on time might sound impractical. That's why the best way to stop starting meetings late is to stop holding so many meetings.

You can't be late to something that doesn't exist.

Research also backs up the "no meetings" approach. Meetings make people less smart; participants placed in small groups and asked to solve problems experienced an individual IQ drop of approximately 15 percent.

Large meetings also stifle participation, especially from people who perceive their status to be relatively low on the group's hierarchy. (Bob from the loading dock is significantly less likely to offer ideas if his boss or, worse yet, the CEO is in attendance.)

As Mark Cuban says, "I don't do meetings or phone calls. I'll do a meeting if you're going to write me a check. I'll do a meeting if there's a really good reason to help close a deal. Other than that, it's email."

Why? Most meetings typically stagger to a late start, and then drift to a slow close. Time gets wasted. Energy gets wasted. Motivation, enthusiasm, and focus get wasted.

All of which makes people much less effective.

So start your meetings on time.

And if you're not willing to do that, maybe you shouldn't have any meetings at all.