Correlations

What is a correlation

Shows the strength and association between 2 co variables

• variables are measured not manipulated like experiments

• Only association is found, no cause and effect relationship so doesn’t use DV and IV

What is correlation coefficient

Number between -1 and +1 that indicated the strength and direction of correlation

• +1 means perfect positive correlation

• 0 means no correlation

• -1 means perfect negative correlation

What is negative correlation

• When 1 variable increases, the other decreases

• Has a negative gradient on scatter gram

What is positive correlation

• When 1 variable increases the other also increases

• Has a positive gradient on scatter gram

What is zero correlation

• No relationship found between co-variables

• No line if best fit can be drawn on scatter gram as points are random

Null hypothesis in correlation

There’s no relationship between V1 and V2

Strengths of correlations

• Quick and economical to carry out- don’t need a controlled environment

• Secondary data can be used in the study (lime government statistics) making it less time consuming

• Used as a starting point to asses patterns between co-variables before doing an experiment

Weakness of correlations

• Hard to establish cause and effect relationship- don’t know which variable is causing the other to change

• 3rd variable may be present, causing the relationship between co-variables

• Correlations are misused/ misinterpreted when made public by the media- correlations presented as causation.