Research methods 9.1.8 - additional research methods and techniques

Question 1

what is a correlational study?

Answer 1

a way of establishing whether there is a relationship between two variables

Question 2

how should a correlational study be conducted?

Answer 2

1. measure the two variables to obtain a set of paired scores
2. analyse the relationship by drawing a scatterplot or calculating a correlation coefficient

Question 3

what does a correlation coefficient do?

Answer 3

tell you the strength and direction of the correlation

Question 4

how should the value of a correlation coefficient be interpreted?

Answer 4

positive number = positive correlation
negative number = negative correlation
the closer the number to 0, the weaker the correlation (+1 and -1 are the strongest possible correlations)

Question 5

how can a correlation be used?

Answer 5

if you know someone’s score on one variable and there is a correlation between the variables, you can predict their score on the other variable

Question 6

what does the accuracy of the prediction depend on?

Answer 6

how strong the correlation is - the stronger the correlation, the more accurate the prediction

Question 7

how do you calculate correlation coefficient using Spearman’s rank?

Answer 7

1. rank the data (separate rank or data in each variable) - lowest gets a rank of 1 and so on
2. find the difference (D) between the ranks for the corresponding data for each variable
3. square D to get D^2
4. add up all the D^2s to get 𝚺d^2
5. find n (total number of pairs of data)
6. substitute the values into the equation to find R (remember to include +/- in final answer)

Question 8

when ranking data, what do you do if you have tied scores?

Answer 8

use up the same number of ranks as there are tied scores, but give all the tied scores the same rank which is the number in the middle of the ranks being used up

Question 9

what are the problems with interpreting a correlation?

Answer 9

the correlation doesn’t tell you which variable is influencing the other
it may be hard to find an explanation for the correlation which could lead to inaccurate assumptions (eg. there may be another variable which isn’t mentioned)

Question 10

what is the key rule to remember about correlation?

Answer 10

correlation does not equal causation (for all correlations, there are at least three possible interpretations)