Lesson 4 Correlation Flashcards
What is correlation
technique for analysing the strength of the relationship between two quantitative variables, known as co-variables.
What is correlation coefficient
strength of the correlation is known as the correlation coefficient.
What are correlations plotted on
scattergram or a scattergraph.
Advantages of correlation
1) Correlations allows psychologists to establish the strength of the relationship between two variables and measure it precisely for example there might be a very strong positive relationship +1 between the variables of being very wealthy and being very happy
2) Correlations allows researchers to investigate things that could not be manipulated experimentally for ethical or practical reasons, for instance a natural relationship might occur between the variables of being highly stressed and having cardiovascular disease. It would be unethical to intentionally inflict stress or cardiovascular disease upon participants, but if it occurred naturally then it would be fine to study this issue
3) Once a correlation has been conducted predictions can be made about one of the variables based on what is known about the other variable. For instance if we know that high stress causes high cholesterol, then we might state that as stress increases, cholesterol might increase. This can help inform conclude that lowering stress might lower cholesterol.
Disadvantages of correlation
1) Correlational analysis cannot demonstrate cause and effect; we cannot tell which variable influences the other. For instance can we sure that high stress causes an increase in cholesterol, or does having high cholesterol cause an increase in stress?
2) Even if there is a correlation between two variables it may be the case that the variables are not actually related but that there is a third unknown variable which influences both. For instance maybe an unhealthy diet might cause an increase in cholesterol (rather than stress causing the increase)?
3) Correlations can only measure linear relationships and does not detect curvilinear relationships. This is when there is a positive relationship up to a certain point but after that the relationship becomes negative or (vice versa).
