I have read far too many news articles with quotes of officials stating “we have more cases because we have done more testing”, and it is really bothering me.
I’ve tried to ignore it, because I’m sure there are better explanations out there, from far smarter people than me; but I just can’t anymore. I feel like I need to say something, if for no other reason than to feel like I contributed to the conversation. So I came up with this simple explanation.
Look at this picture:
This is just a simple pic I made of blue and red dots. I didn’t count how many of either, but it doesn’t matter. Now; look at this pic:
Exactly the same pic, just with a circle on it.
Lets pretend the dots are people; the blue dots are healthy people, and the red dots are sick people, the dots inside the circle are the people you tested.
Now the tricky part, the total number of red dots in the whole picture does not change, no matter how big (or small) the circle is.
Testing reveals cases, it does not create cases.