Numbers crop up in media stories in the most unexpected places. Your goal is to provide context and the story behind the numbers. Here's how you can write about two terms — risk and rate — accurately and ethically.

A rate compares quantities that are measured in different units: for example, an amount or frequency over time or other unit. Think of miles per hour, dollars per barrel, words per minute. Incidence per 100,000 residents can be used to compare numbers of sick people or murdered people or burglarized homes with a population as a whole.

The risk is the likelihood of something happening. Comparing rates can help you figure out the risk of something happening. You provide context when there are fears of unlikely events. For example, in 2014, according to CDC, 86,000 elderly Americans were hospitalized for influenza; 4 people (of any age) were diagnosed with Ebola in the United States. While people were far more frightened of Ebola, the risk was much, much greater of getting sick with — and even dying of — the flu.

Why look at risk? When the PowerBall jackpot topped \$1 billion, hundreds of thousands of people who don't usually play bought tickets. But the chance of winning was 1 in more than 292 million. As Ron Wasserstein, director of the American Statistical Association, told NPR, "You would need to buy 1,000 lottery tickets to have the same probability of winning the Powerball jackpot as you would have to pick the one penny out of the stack the height of the Empire State Building." Not great odds.

Taken from Numeracy Primer: How to Write About Numbers, a self-directed course by Pam Hogle at Poynter NewsU.

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