Correlations

Correlation definition?

a research method used to establish if there is a relationship between two covariables using mathematical techniques

What does correlation demonstrate?

the strength and direction of a relationship between two or more covariables

Covariables?

the variables investigated in a correlation - one covariable forms the x-axis and another forms the y-axis

Why are the covariables not referred to as independent and dependent variables?

a correlation investigates the association between the variables, rather than trying to show a cause and effect relationship

Positive correlation?

as one covariable increases, the other covariable also increases

Negative correlation?

as one covariable increases, the other covariable decreases

Zero correlation?

there is no correlation (relationship) between two covariables

Correlation coefficient?

a number between -1 and +1 that represents the direction and strength of a relationship between covariables

Correlation coefficient: -1?

perfect negative correlation

Correlation coefficient: +1?

perfect positive correlation

Correlation coefficient: 0?

no correlation

Correlation - strength 1: what type of tool are they?

a 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 - so correlations are usually used as a starting point to assess possible patterns between variables before researchers commit to an environmental study

Correlation - strength 2: in what ways are they better than experiments (2)?

quicker and more economical to carry out - no need for a controlled variables and no manipulation of variables is required and secondary data can be used

Correlation - weakness 1: what can’t they demonstrate?

cause and effect between variables - due to the lack of experimental manipulation and control, correlations can only tell us how variables are related and not why - so we don’t know which co-variable is causing the other to change

Correlation - weakness 2: key problem?

third variable problem - may be the case that another untested variable is causing the relationship between the two co-variables we are interested in