Measuring disease and understanding risk

If someone were to tell me there were 5 sick people he would be telling me a _______

count

5 sick people/ 25 total people is a ________

proportion

5 sick dogs/dog month is a _______

rate

5 sick dogs: 25 not sick dogs is an _____

odds

A condition of interest would be considered an _________

outcome

The risk of being a case is known as _______

prevalence

The risk of becoming a case is known as ________

incidence

To calculate incidence rates you must divide the total number of outcomes by the ________ of each individual

total time

If you multiplied incidence by duration you would get what

prevalance

What are considered measures of association

• odds ratio

• relative risks

What is considered a measure of effect

• risk difference

How would you calculate the risk of being exposed in a 2 × 2 table

Divide the number of those with the disease that were exposed by the total number of people exposed

How would you calculate the relative risk ratio

divide the risk of being exposed by the risk of being unexposed

Having a RR less than 1 means what

There is a decreased risk of disease if exposed

Having a RR greater than 1 means what

there is an increased risk of disease if exposed

How would you calculate the odds ratio

divide the odds of being exposed by the odds of being unexposed

Having an odds ratio greater than 1 means what

there is an increased odd of disease if exposed

Having an odds ratio less than 1 means what

There is a decreased odd of disease when exposed

A risk difference greater than 0 means what

exposure is positively associated with disease

A risk difference less than 0 means what

exposure is protective

When would prevalence be equal to incidence

if length of disease is short