Ready to play Hide and Seek?
Or are you just ready to hide?
Most people feel like hiding when faced with the numbers that health and medical professionals use daily, statistics. So we’re going to start slowly and cover different mathematical concepts you might have heard. This will be a series of posts so if there are any math concepts that you aren’t familiar with, write us in the comment section below and we’ll try to tackle them.
So take a DEEP BREATH (count 5 seconds)…
Okay, breathe out! (count 5 seconds) Now…
What does Incidence mean?
Here’s a definition from the Dictionary of Epidemiology: ‘the number of instances of illness commencing, or of persons becoming ill’ (or dying or being hurt in injuries, or whatever) ‘during a given period in a specified population’. Most of the time when you read or hear incidence, the person using the terms is saying incidence rate. That’s the rate at which events occur in a population.
Clear as mud, right? Let’s go through an example (from here) and see if we can clear this up.
Here’s the definition again with different words highlighted in different colors.
“the number of instances of illness commencing, or of persons becoming ill’ (or dying or being hurt in injuries, or whatever) ‘during a given period in a specified population’
Suppose you have a group of 200 women in a study. During 2012, 5 of those women were diagnosed with breast cancer.
What is the incidence rate of breast cancer in this population of women? (Here’s where anyone with math anxiety begins to sweat profusely…try the deep breathing technique again now!)
We have to do division: Divide the number of women who get the disease divided by the number of women in the group or (population) in 2012. Remember the time period is important!
OKAY…we got a number but it really doesn’t mean anything to most people. What happens next? We can say that the incidence rate in the population of 200 women during the year 2012 is .025. Or epidemiologists will project that the incidence of breast cancer is 2,500 per 100,000 women during the years of the study. *
The way they get this figure is they multiply 100,000 X .025 figuring that people can understand 2,500 better than .025.
Here is a picture that shows this proportion:
When you hear an incidence number from a health care provider, ask for a picture like this pie chart. It can really clear up muddy waters.
Are you still breathing?
If you have any questions about this, don’t hesitate to ask.