WSJS newsman does not understand divorce rate

For the second day now, I've caught WSJS's newsman Smith Patterson reporting on Rockingham County's high divorce rate. A rate of over 15%, highest in North Carolina -- he says.

Wrong.

Patterson is reporting that 15% of the people living in Rockingham County are divorced and calling it the divorce rate. That is not the divorce rate.That is a measure of marital status--not the same thing. The divorce rate measures the rate at which marriages end in divorce not the percentage of people in any given population who are divorced.

Think of it this way. If you wanted to know a county's school system's graduation rate, would you measure the number of high school seniors who graduate from among the high school seniors in that system or would you measure the percentage of the entire county population who have a diploma? One thing would measure the schools' graduation rate, the other would measure the populace's educational attainment, two different things. Smith Patterson is erroneously reporting the populace's marital status as the county's divorce rate.

There are two big mistakes in saying that the divorced percentage of the population reflects the divorce rate.

1. A divorce rate must measure against marriages, not against the population at large (Children and other people never married cannot meaningfully be included in the population from among which the rate of divorce is measured). A county that has 1,000 marriages with 400 of them ending in divorce has a higher divorce rate than the county that has 10,000 marriages ending in 400 divorces -- same number of divorces, different divorce rates.
   
2. It fails to account for people moving in our out of the county. If I get divorced in Florida then move to Rockingham County, I contribute to the percentage of divorced people in Rockingham County, but I do not contribute to the percentage of marriages ending in divorce (the divorce rate) in Rockingham County because my marriage did not end in divorce in Rockingham County.

The Winston-Salem journal gets it right, reporting accuratley on the percentage of people living in Rockingham County who are divorced. WSJS's Smith Patterson, in reporting that this is the divorce rate, is just wrong.