Keller @ Large: How To Read Presidential Polls

BOSTON (CBS) - Everywhere I go, people ask me about the latest polls, and no wonder.

We in the media make a big deal out of them, and so do the candidates. Donald Trump used to spend a big chunk of every speech going over the polls, until they turned sour for him.

But I also find many people are confused about what polls mean and how to read them.

So here are a few tips on how to put the polls in perspective.

First of all, in the presidential race, national polls are virtually meaningless. Massachusetts is going to go for Hillary Clinton; Mississippi will vote Trump.

Instead, look at the swing states: Colorado, Florida, Iowa, Michigan, Nevada, New Hampshire, North Carolina, Ohio, Pennsylvania, Virginia and Wisconsin. History shows that's where the race will be decided.

When you look at a poll, move quickly past the horse-race numbers for the real meat: questions that gauge voter mood and how the candidates are perceived. Then look for the crosstabs, the demographic breakdowns within those responses.

Take special note of what independents are saying, they are usually the voters who are up for grabs.

Look for gender gaps, and what the most reliable voters – those age 40 and up – are thinking.

And look for long-term trends. For instance, Trump hasn't polled beyond the low 40s all year, and Clinton has rarely touched 50 percent.

That's telling.

But most of all, don't ever let the polls substitute for your voice, or suppress it.

Because while it may be the ultimate political cliché, it's also true – the only poll that counts is the one on Election Day.

Listen to Jon's commentary: