Grammar Moses on percentages, incidences ‑ hey, is this a grammar column?

Years ago when Cook County officials first talked about raising its sales tax rate to 10 percent from 9 percent, I heard discussions and read words describing it as a 1 percent tax increase.

Were that only the case.

Have I mentioned before that I was pursuing a life in numbers before I took a hard left and ended up here?

Mathematical blunders in journalism are like potholes in February. There is one waiting for you to fall into around every corner.

An increase to 10 from 9 is 11.1 percent. As I tell math-challenged reporters on occasion, subtract the old number from the new number and divide that result by the old number.

A 1 percent increase from 9 percent would be just 9.09 percent.

My point is that when one talks about raising the rate to 10 percent from 9 percent, one should refer to it as a 1 percentage point increase, not a 1 percent increase.

Incidents/incidence

Beware these homophones!

These words sound exactly alike and are often written as if they were the same word. While they are related, they are not one and the same.

An "incident" is an occurrence.

"Bob was in a fender bender. The incident left him with a sore neck and a big repair bill."

The primary definition of "incidence" is the rate at which something occurs.

(I will spare you the dissertation on "incidence" as it applies to light refraction.)

"The growing incidence of smash-and-grab burglaries at commuter parking lots is alarming."

Further muddying things are those who believe "incidence" as a word synonymous with "incident" and pluralize it by tacking on an "s."

You shouldn't say or write that there were several incidences of vandals cutting down parkway trees.

The only time you'd want to write about incidences is if you are describing more than one rate of occurrence. Between you and me, with that many variables it sounds almost like physics. Best to avoid that!

In to or into?

Sometimes in our haste to post a story to dailyherald.com we are so focused on getting the facts right that we sometimes fail to make sure our spelling and grammar are up to snuff.

Given that the faster we post something the larger audience we have for the rest of the day, it's important to put our best foot forward right out of the gate.

When it was announced on Wednesday that disgraced Fox Lake cop Joe Gliniewicz's wife, Melodie, had been indicted on money laundering charges, we posted a story before the competition that noted she had "turned herself into police."

I've covered this issue in this space already, but it bears repeating.

One cannot turn oneself into police without a magic wand. You don't visit the police department and - poof! - you're a cop.

Unless, of course, you're there to be sworn in. Even then, someone other than you is turning you into a cop.

You can, however, turn yourself in (exaggerated pause) to police.

The beauty of the web is that we can fix mistakes like that in a matter of seconds.

Write carefully!

• Jim Baumann is assistant vice president/managing editor of the Daily Herald. Write him at jbaumann@dailyherald.com. Put Grammar Moses in the subject line. You can friend or follow Jim at facebook.com/baumannjim.