Week 2: Epidemiology

Question 1

2 facets of epedimiology

Answer 1

How common is a problem

Who has the problem

Question 2

How common is a problem (incidence/prevalence)

Answer 2

incidence - new cases over a time period

prevalence - all cases (new and old) over a time period

eg 6 months/one year/lifetime prevalence

Question 3

Why do we sample/problems with sampling

Census example

Answer 3

To infer something about the population

If the sample is not representative, this ruins this

All Canadians must finish the short form census, 20% do the long form. This 20% is carefully chosen. The Tories wanted to make this voluntary. This would have ruined the generalizability as there may have been significant differences between the group the filled out the long form census and those that did not.

The liberals made it mandatory again.

Question 4

2 sample types

Answer 4

Random sampling - everyone in population of interest has an equal chance of being chosen

Sample of convenience - sample who is readily available
Not random
Unfortunately common in psychology

Question 5

Participation rate

Answer 5

When you do random sampling, some people will agree and participate, some wont.

You have to watch this as people who do not may differ from people who do

Question 6

External validity

Answer 6

The extent to which findings generalize

Question 7

Who has the problem

Answer 7

Assess factors that influence rates and distribution of a disorder in a population

Such as demographic factors
Age
Gender
SES

Question 8

Correlation is…

Answer 8

not causality (how many times)
It is often reported as if it is

You may get SPURIOUS correlations

Question 9

Causality requires 5 things

Answer 9

1) Theoretical expectation that A would cause B
2) A and B have to be related empirically (correlation)
3) Elimination of other possible causes
4) Temporal ordering; A occurs before B
5) Responsiveness: Changing A leads to B changing