# It is official!

I hate Epidemiology.

Owww!!! It so pains me to hear that… but I don’t blame you if it was taught to you the way it was taught to my classmates. Just know that real epidemiology can be a lot of fun. You’ll have to trust me on that one
Anyway, if there is anything I can do to help, I’ve been told that I explain epi stuff pretty well.
Epidoc

That picure is so funny. Sorry to hear you hate that class. Epidemiology and Pharm are the 2 classes I am most worried about.

Quote:

Anyway, if there is anything I can do to help, I’ve been told that I explain epi stuff pretty well.
Epidoc

ok, got any tips on UNDERSTANDING the 2x2? I swear that I know it is easy, but the cross over configurations, vis-a-vis A/A+C - Present
Some of it just gets me lost. She hammers this stuff endlessly. I know it should be simple, I just get confused whenever I get to it.

The 2 x 2 table can be tricky, mostly because people use it differently, and it changes depending on what type of study is being analyzed (retrospective or prospective). When I’m tutoring, I always make people write out the words on the top and on the side, and try not to use the letters at first.

Let’s use smoking and lung cancer as an example.
I always set up the tables with “Truth” (are they REALLY sick or well) on the top of the box, and then “Test Result” or “Exposure” on the left side, with + on the left top box, and - on the right top box, and on the side + on top. Once I’ve got that set up, I can think about what goes in each box. So in box A would be all the people who really are sick and smoked. Right beneath that would be the people who really do have lung cancer, but didn’t smoke. I always expand the box then, and have the total-- which would be the total number of people who really have lung cancer, which would be A+C. So A/A+C would be the number of lung cancers in smokers, over the total number of lung cancers. That would give you the rate of lung cancers among smokers. C/A+C would give you the rate among non-smokers, and you can compare the two.
The tricky thing is that when they give you the little formulas for figuring out rates by cross multiplying and such they are assuming you set the table up in a particular way. You need to always check how the table is being set up. For retrospective studies (like you would use in an outbreak investigation), you usually put well people on the top and sick people on the side, and the + and - indicate their exposure. The difference is, in prospective studies you know beforehand if people are exposed or not, and then you watch to find out who gets sick, and in retrospective you know who is sick and you group them that way, and then you figure out if they were exposed or not.
Hmmmm… I hope that is clear. If you let me know what you are using the 2 x 2 to figure out, I could probably be more helpful. It is a bit harder to explain this way, then when I have folks making big 2X2 tables on a whiteboard The key thing is not to get too caught up in the formulas at first-- work on figuring out exactly what you are putting in each box, and what you are trying to figure out. Once you are a little more comfortable with that, the math tends to make more sense.
I don’t know if that answered your question, or was any help but if you have specific questions and examples, those are a little easier to explain. Feel free to PM me if you’d like.
Epidoc

Futrysician,
You really need to stop beating around the bush. Stop sitting on your emotions, and say what you mean, you know just…spit it out

Oops! When I wrote the explanation, I was kind of rushing, and just realized I made an error. Where I was saying how to get the rate of cancer in non smokers in the example? Of course it would be c/c+d, not c/a+c … which sort of makes my point-- try to think in words not formulas, because formulas get mixed up easily!
Sorry for adding confusion
Epidoc

For what its worth, I’ve always actually liked epidemiology. I know that probably doesn’t suprise JP sense he already thinks I’m a weird Aggie
I had a great epi professor in grad school who taught it as a means to solve mysteries. I still love the story about Snow and cholera.
In medical school, we didn’t have an epi course. We did, however, spend enourmous amounts of time learning how to ‘do’ EBM. Obviously, biostats and epidemiology was a big part of that.
Take care,
Jeff

Quote:

That picure is so funny. Sorry to hear you hate that class. Epidemiology and Pharm are the 2 classes I am most worried about.

I was SO scared of pharmacology before I took it. I think the reason was I had envisioned endless lists of drugs with random information attached to it that I would have to memorize, and I wasn’t sure my brain worked like that anymore. Turns out, it wasn’t like that, and it ended up being one of my best classes. Unfortuately, I freaked out before the class and bought every review book, flash card and supplement I could get my hands on, and then ended up using very little of it.
Don’t worry, it is not as “list-y” as you think.

Hi there,
I have one solution to your Epi problems:
High Yield Epi and Biostats
I read it in one day and honored the class. Well written and easy to understand.
Natalie