12. correlations

what is a correlation

a mathematical technique in which a researcher investigates an association between two variables (co variables)

what are they plotted on

a scattergram

what are co variables

• the variables investigated within a correlation

• they are not referred to as the IV/DVs as a correlation investigates the association between the variables, rather than trying to show a cause and effect relationship

types of correlation

1. positive

2. negative

3. zero

positive

as one co variable increases so does the other

negative

as one co variable increases the other decreases

zero

when there is no relationship between the co variables

differences between correlations and experiments

• experiment = control/manipulate the IV to measure effect on the DV

• correlation = there is no such manipulation of a variable so you cannot establish cause and effect

evaluation

1. preliminary tool

2. economical

3. establishing direction

4. third variable

preliminary tool

• useful preliminary tool for research

• by assessing the strength and direction of a relationship, they provide a precise and quantifiable measure of how two variables are related

• often used as a starting point to assess possible patterns between variables before researchers commit to an experimental study

economical

• relatively quick and economical to carry out

• no need for a controlled environment and no manipulation of variables is required and data collected by others (secondary data eg gov statistics) can be used, meaning they are less time consuming than experiments

establishing direction

• lack of experimental manipulation and control means studies can only tell us how variables are related

• cannot demonstrate cause and effect so establishing the direction of the effect is an issue

third variable

• may be the case another untested variable is causing the relationship between the co variables - an intervening variable (third variable problem)