Epi/Biostats

Question 1

A sample of children age 2-5 years is chosen at random from an outpatient clinic. The number or UTIs over a year is shown in the figure below. What was the average number of UTI episodes over a 1 year for a child in this sample?

Answer 1

[(0 x 50) + (1 x 30) + (2 x 10) + (3 x 10)] / 100

.8 UTIs for a child in this sample

Question 2

What is a cross-sectional study? Can it identify causality?

Answer 2

A cross-sectional study measures PREVALENCE

you are basically trying to figure out how many people have the disease and how many people have the exposure at one point in time

NO! it does not establish causality

Question 3

What is a case-control study? What equation do you use to determine risk?

Answer 3

you identify a group of people with the disease, then compare them to a similar group without the diease. Look to see if prior exposure or risk factor differs by disease state

Odds ratio

Question 4

What is a cohort study? What equation is used to determine risk of developing disease?

Answer 4

identify a group with a specific exposure and one without said exposure. Then follow them to and identify individuals who get disease.

relative risk

Question 5

in women, what are the most common cancers that affect women?

Answer 5

incidence: Breast > lung > colon
deaths: lung > breast > colon