module 4

Question 1

What is the definition of epidemiology and how does this relate to descriptive and analytical view points

Answer 1

Epidemiology is the study of the distribution and determinats of health related states or events in a population

Descriptive relates to distribution
- people, place or time
- who, when, what, were

Analytic relates to the determiates
- outcomes and exsposure (observational or analytic)
- corrolated
- WHY

Question 2

What is a cross sectional study

Answer 2

A Descriptive epidemiological study

a study which measures exsposure and/or outcomes for a population at a point in time

• Date, time period, event

Question 3

What can be measured from a cross-sectional study

Answer 3

measured:
Prevlance - duration + incidence
used -
- describe prevlance
- compaire prevlance - age or time
- Generate a hypothesis
- plan resourse allocation

Question 4

What are the limitations and strengths of a cross sectional study

Answer 4

Limitations:
- Dont know temporal sequence
- No measure of incidence
- Bad for rare outcomes
- Not good for outcomes which vary over time

Strength:
- Cheap
- Time efficent
- Look at multiple exsposures
- Dependant on reserch question
Do we want a hypothesis? Are we looking at a stable population? Do we want a measure of prevelance?

Question 5

What is a GATE for frame

Answer 5

graphic apprasal tool for epidemiology

triangle = sample from population
circle = top = exposed, bottom = control
square = left has condition or right doesnt have condition still top bottom specific

Question 6

What is the prevlance ratio

Answer 6

The relative risk
exposed + outcome / contol + outcome

Question 7

What is an ecological study and when are they used

Answer 7

A descriptive epidemilogical study
compair exsposure and outcome of a group
- No data about the individual

used for:
- comparison between populations
- assessment of a populations risk factors
- consider a hypothesis (check if it matches)

Question 8

What are the strengths + limitations of an ecological study

Answer 8

Limitations:
- Ecological falocy = cannot make a prediction about an individual based around a population
- Cant control confounding
- cannot show causation

Strengths:
- data offten collected regulaly = easy to do + cheap
- dependant on reserch question, is it a population level exsposure? do we want to consider a hypothesis?

Question 9

What is index dating

Answer 9

Used in case control study
taking your control at the same time as you add a case to the study