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Good Questions: Black Friday, Margin Of Error & Sleep-Falling Out Of Bed

MINNEAPOLIS (WCCO) -- Every Friday, Good Question takes a look at some of the questions WCCO's viewers have been asking. This week we're looking at Black Friday, margin of error, and falling out of the bed while sleeping.

Janelle from Lake Lillian and Dave from St. Paul Park want to know: How did Black Friday start?

It didn't start out great.

Back in the 1950s, police officers in Philadelphia used the term to refer to the shopping madness of that day, including the crowds and traffic. But, in the 1980s, retailers got smart and took over the name for the day when profits for the year go from red to black.

Since 2005, Black Friday has consistently been one of, if not, the largest shopping days of the year in the US.

Dan asks: What does the margin of error tell us?

Polls are done by taking a sample of people, not the whole population, so the margin of error tells us how much that sample may be off.

"Sampling error is one of the dozen or so indicators of quality," says Rob Daves of Daves & Associates Research. "Sampling error tells you how confident you can be about the point estimates within the poll."

For example, if Marco Rubio is polling at 16 percent and the margin of error is 5 percentage points, Rubio could be polling as high as 21 percent or as low as 11 percent. Pollsters are generally 95 percent confident of that result.

Generally, the larger the margin of error means the smaller the sample size of the poll.

Dianne from Ortonville wants: Why don't we fall out of bed when we sleep?

According to Dr. Michael Howell, a sleep expert with the University of Minnesota, we're still subconsciously aware of our environment when we're sleeping.

Small children are more likely to fall out of bed because they sleep more deeply and haven't yet learned that awareness.

Dr. Howell says if any adults fall out of bed while sleeping, that person should be checked out by a doctor.

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