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Epidemiology & Biostatistics > Cohort Studies > Flashcards

Flashcards in Cohort Studies Deck (9)
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1
Q

What is a cross sectional study?

A

One where the exposure and disease status of patients is measured st a single point in time only

2
Q

What is the prevalence ratio?

How is this calculated?

A

The prevalence of the disease in the exposed

Divided by

The prevalence of the disease in the non-exposed

See notes for help.

3
Q

What is the prevalence odds ratio?

How is this calculated?

A

The odds that a diseased person was exposed to the exposure in question

It is the cross table multiply and divide (see sheet for help).

4
Q

What are the prevalence odds?

How are these calculated?

A

The odds that a diseased person was exposed

And

The odds that a non-diseased person was exposed

5
Q

With respect to cohort studies, what X3 time frames can they cover?

A

1) retrospective
2) prospective
3) bi-directional

6
Q

What is the relative risk (incidence proportion or cumulative incidence)?

A

It is the number of new cases out of the people at risk at the start of the study (times stated number)

It looks at the stats at the end of a given period of time, whereas relative risk (ID) looks at the rate of development of a disease.

7
Q

What is the relative rate (incidence rate or density)?

A

It is how fast a disease develops

It is the number of new cases / total person-time years

9
Q

What is the rate ratio in cohort studies?

A

The rate of disease in the exposed

Divided by

The rate of disease in the unexposed

= a/(a+b) / c/(c+d)

10
Q

What are person years?

A

It is a way of defining the number of cases observed in a time frame when different participants contribute different lengths of time to the study.