Scioly.org

Are there any resources for examples of statistical analysis questions that I can use?

Hello,

I am currently in division B. Is there any useful tips and stuff that I can study before my invitationals?

maxxxxx wrote:

megan_scioly wrote:is there a place we can get tests that regard the current subject?

Tests from 2011 and 2012 on the Test Exchange are from the last time the topic was foodborne illness

That is really smart! I never really thought about that!!!

Vince wrote:Hello,

I am currently in division B. Is there any useful tips and stuff that I can study before my invitationals?

I'm not sure what specific things you need help with, but definitely read the Wiki since it covers the basics of each part of the event. The CDC has good 10 minute lessons if you need to study things like epi curves or risk factors. Make sure you know your vocab because every test I've taken except for one has had the same matching section with vocab.

Does anyone have a list of the bare minimum I would need on a cheat sheet for Disease Detectives? I'd like to improve last year's cheat sheet...(It was bad.)

What is the difference between Division B and Division C? As others have said, ideally Division C exams are more difficult - for Division B you should be able to define, describe and calculate, in Division C you should be able to discuss, explain and evaluate. Division C includes experimental error, stratified analysis, and descriptive and analytic statistics Division B does not.

Is cholera a foodborne illness? - Yes, it can be. Check out https://www.cdc.gov/foodsafety/diseases/index.html for a list of foodborne pathogens..

What to study. I strongly suggest using the Principles of Epidemiology 3rd edition (https://www.cdc.gov/ophss/csels/dsepd/ss1978/ss1978.pdf) as a source. Although a lot depends on who is writing the event, if you have really mastered the material in that book, you should do quite well in almost any competition.

The explanation for why one uses an odds ratio rather than relative risk for case control studies was right on. Good job. You will sometimes see odds ratios used in cohort studies - it is easier to control for several different variables using an odds ratio rather than a relative risk. You will not see relative risk used for a case-control study. Can't be done that I know.

Good luck in the coming season. See you in Ohio.

Private Wang Fire wrote:

Unome wrote:So I read today that Odds Ratio should be used for Case-Control studies because Relative Risk can't be measured. Can someone explain to me why this is the case?

In a case control study the total number of people exposed to the exposure being investigated isn't known, so you can't calculate the true risk or relative risk, which is why we use odds ratio instead!

I love asking people in disease at my school this question

I still don't really understand. Why is the total number of people exposed known when doing a cohort study if it involves a sample? Why is it not known in a case-control?

Unome wrote:

Private Wang Fire wrote:

Unome wrote:So I read today that Odds Ratio should be used for Case-Control studies because Relative Risk can't be measured. Can someone explain to me why this is the case?

In a case control study the total number of people exposed to the exposure being investigated isn't known, so you can't calculate the true risk or relative risk, which is why we use odds ratio instead!

I love asking people in disease at my school this question

I still don't really understand. Why is the total number of people exposed known when doing a cohort study if it involves a sample? Why is it not known in a case-control?

Cohort presumes that you are tracking the entire exposed/unexposed population to the outcome, whether they develop the disease or not. Case-control starts with the outcome, so when you go back towards whether they were exposed/unexposed, you don't have the whole population, just a sample. Does this make sense? I'm not a very clear explainer

Private Wang Fire wrote:

Unome wrote:

Private Wang Fire wrote:
In a case control study the total number of people exposed to the exposure being investigated isn't known, so you can't calculate the true risk or relative risk, which is why we use odds ratio instead!

I love asking people in disease at my school this question

I still don't really understand. Why is the total number of people exposed known when doing a cohort study if it involves a sample? Why is it not known in a case-control?

Cohort presumes that you are tracking the entire exposed/unexposed population to the outcome, whether they develop the disease or not. Case-control starts with the outcome, so when you go back towards whether they were exposed/unexposed, you don't have the whole population, just a sample. Does this make sense? I'm not a very clear explainer

So why can a cohort study generalize a determined relative risk to a broader population of people? (or can it just not?)

Unome wrote:

Private Wang Fire wrote:

Unome wrote: I still don't really understand. Why is the total number of people exposed known when doing a cohort study if it involves a sample? Why is it not known in a case-control?

Cohort presumes that you are tracking the entire exposed/unexposed population to the outcome, whether they develop the disease or not. Case-control starts with the outcome, so when you go back towards whether they were exposed/unexposed, you don't have the whole population, just a sample. Does this make sense? I'm not a very clear explainer

So why can a cohort study generalize a determined relative risk to a broader population of people? (or can it just not?)

The "population" in the case of a cohort is the entire exposure group, as in everyone who was exposed to that specific exposure at the specific time and place in the case study, which means relative risk can be used.

In the case control, the cases or controls you select initially represent only part of the total "population" that you're studying - population in this case would be defined to strictly those with nearly identical (in an ideal case) characteristics and the only thing that sets the two groups in the study apart would be whether they were exposed or not.

So not like a broader population of people, just like the population that is involved in the disease 'event' or whatever.