correlations

Question 1

what is a correlation?

Answer 1

a mathematical technique where a researcher investigates an association between two co-variables

Question 2

what are co-variables?

Answer 2

• the variables investigated within a correlation eg. height and weight
• they are not referred to as the independent and dependent variables because a correlation investigates the association between the variables rather than trying to show a cause-and-effect relationship

Question 3

where and how are correlations plotted?

Answer 3

• on a scattergram
• one co-variables is represented on the x-axis and the other on the y-axis
• each point on the graph is the x and y position of each co-variable

Question 4

what is a positive correlation?

Answer 4

• as one co-variable increases so does the other
• eg. the number of people in a room and noise tend to be positively correlated

Question 5

what is a negative correlation?

Answer 5

• as one co-variable increases the other decreases
• eg. the number of people in a room and amount of personal space tend to be negatively correlated

Question 6

what is a zero correlation?

Answer 6

when there is no relationship between the co-variables

Question 7

what is the difference between correlations and experiments?

Answer 7

• in an experiment, the researcher manipulates the IV to measure the effect on the DV
• this deliberate change in one variable makes it possible to infer that the IV caused any observed changes in the DV
• however, in a correlation, there is no manipulation of one variable so it is not possible to establish cause and effect between one co-variable and the other
• even if we found a strong positive correlation between two co-variables, we cannot assume that one caused the other

Question 8

what are curvilinear relationships?

Answer 8

• some relationships are more complicated than positive or negative correlations
• the yerkes-dodson law of arousal states that performance is at its best when there is a moderate (optimal) level of arousal and will deteriorate if the arousal level is too low or too high

Question 9

evaluation: useful preliminary tool for research

Answer 9

• by assessing the strength and direction of a relationship, they provide a precise and quantifiable measure of how two variables are related
• this may suggest ideas for possible future research if variables are strongly related or demonstrate an interesting pattern
• therefore, correlations are often used as a starting point to assess possible patterns between variables before researchers commit to an experimental study

Question 10

evaluation: relatively quick and economical to carry out

Answer 10

• no need for a controlled environment and no manipulation of variables is required
• data collected by others (secondary data eg. government statistics) can be used, which means correlations are less time-consuming than experiments

Question 11

evaluation: correlations can only tell us how variables are related but not why

Answer 11

• due to the lack of experimental manipulation and control within a correlation
• cannot demonstrate cause and effect between variables so we don’t which which co-variable is causing the other to change
• therefore, establishing the direction of the effect is an issue

Question 12

evaluation: intervening variables

Answer 12

• it may be the case that another untested variable is causing the relationship between the two co-variables we are interested in
• this is called an intervening variable (aka the third variable problem)

Question 13

evaluation: occasionally misused or misinterpreted

Answer 13

• largely because issues such as intervening variables and knowing how but not why, correlations can occasionally be misused or misinterpreted
• relationships between variables are sometimes presented as causal when they aren’t
• eg. in the claim that people from ‘broken’ homes become criminals, an intervening variable, such as poverty being a cause of a broken home and also the key factor in criminality, might explain the apparent link