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You use a 2 x 2 table.

A B
C D

So pretend A = 30, B = 36, C = 10, and D = 70. The odds ratio would be 30 x 70/36 x 10 = 5.8. A is the number of case patients exposed, B is the number of the control group exposed, C is the number of case patients unexposed, and D is the number of the control group unexposed. (I'm pretty sure that's it.)

And if you need anymore clarifications, the Training Handout would be a really good resource.

srsvball95 wrote:No, attack rate can be used in any study design

Actually, it can't - at least, not in the same way. In a cohort study or an ecological analysis, you have a defined population with some number of affected people, so you can do an attack rate. Note that attack rate is basically synonymous with risk, and that relative risk is the ratio of attack rates. In a case-control study, typically your cases are all affected by whatever disorder you are investigating, your controls are unaffected, and you are trying to correlate an outside factor. Attack rate is not very useful here - it will be near 100% for cases and near 0% for controls, as a matter of definition.

what should I memorize, there is so much that is recomended ?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

Uumm... I know. There's a lot of information, and that's what makes Science Olympiad so challenging.

Well, you might want to look a little at the Wiki and the Training Handout. For Disease Detectives, you'll want to print out and do a lot of practice tests.

Hey, this is my first time doing this event for Div C. I did it once (2 years ago) in Div B and got 3rd at regionals w/o really studying, but it'll probably be a lot harder now.
I'm not really sure how to study.
I know that looking at the wiki/ training handout is helpful. Is the online textbook Principles of Epidemiology helpful also? Or would I be better off studying some of the other links.
Thanks!

It'd probably be helpful. Also, run some searches on Google on specific stuff you want to know about. To study, my coach told us to make a PowerPoint, which is really helping me learn a lot of stuff. If you go to the official Science Olympiad website (soinc.org) there's a lot of links as well that you can check out. I would say study everything that you can plus as many textbooks as you can get your hands on. For Regionals and State in Division C, it's sort of hte same thing, except you have to be able to recognize differences between study designs, calculate measures of risk wehn given a description of the study design, calculate measures based on data that is not given but that can be readily extracted, and recogniz how gaps in information influence the ability to extend conclusions to the general population. So, that means that Division C should sort of be like Division B, except you go more in depth and you have to calculate more stuff. The calculation will probably get harder too, since they are developed based on grade level/division.

quadratic wrote:what should I memorize, there is so much that is recomended ?????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????

Start with the basic vocab and let me tell you flashcards are great for that. Then once you know have memorized the basic vocab go over the following equations: attack rate and relative risk. Relative Risk was always espicially hard for me, idk why though... lol After those just start taking practice tests, that is by far the best way to prepare yourself.

Basic Disease Terms: Epidemiology, Epidemic, Pandemic, Outbreak, Fomite, Vector and Host. See the training handout though for many more vocab terms you should get to know.

this year's focus (for B) is food borne diseases, so I would just put some major food borne agents on the note sheet.
also theres a lot of math involved
actually odd ratio can be used with any study design, not attack rate

I would memorize as much as I could and put some key concepts on my notesheet and some things that I can't remember.

deezee wrote:I would memorize as much as I could and put some key concepts on my notesheet and some things that I can't remember.

Here's how I see it: this event is not so much about memorization, but about understanding concepts of epidemiology. It means nothing to memorize a bunch of formulas when they would take up virtually no space on your note sheet, instead focus on understanding what the formula represents and when/how you would use it. Simplified Example:If you don't know how to use relative risk, instead of memorizing the formula, use up one tiny part of your sheet to write down the formula and instead understand what relative risk means(note that this example is meaningless for most people, for after you have taken so many practice tests, you will have memorized the formula anyway). Many times on a DD test, they will ask you to calculate some ratio or other, and then ask about the implications of the result, so you will need to know what your formulas mean. I appreciate the including of a note sheet in this event , even though people say there is not much you need to know for the event; if you decide to be an epidemiologist in real life, you will not need to memorize every formula by rote, but you will need to understand how to use and apply the results. [/rant]

deezee wrote:this year's focus (for B) is food borne diseases, so I would just put some major food borne agents on the note sheet.
also theres a lot of math involved
actually odd ratio can be used with any study design, not attack rate

Also correct me if I'm wrong on this, but odds ratio is only actually useful on a case-control study. Odds ratio can be found with a cohort study, but it is meaningless, you need to use relative risk. Both odds ratio and relative risk are approximations of the risk ratio, in a case-control study, you attempt to find common exposures that may have caused the disease. You use a small sample of people with the disease and a larger sample of people without the disease and try to find differences in certain factors. Thus, if using the 2x2 table, a+b is approximated to be b and c+d is approximated as d. With a cohort study, you test people who have been exposed to a factor or unexposed, and compare the likelinesses of contracting the disease, this comparison is made using relative risk (sorry if that made no sense to you).