Y13 RESEARCH METHODS - TESTS OF CORRELATION : Spearman's and Pearson's

Question 1

why is spearman’s rho used?

Answer 1

• used when one or both of the variables are ordinal level
• test of association between two set values
• non parametric

Question 2

Summary of how to do spearman’s rho test?

Answer 2

1. table of ranks = rank each set of scores SEPARATELY
2. calculate difference between each pair of ranks
3. square the difference
4. calculate rho
5. calculated > critical = significant difference

Question 3

why is pearson’s r used?

Answer 3

• used when the data is interval level
• parametric test

Question 4

Summary of how to do Pearson’s r test?

Answer 4

1.table of data = calculate sum of x and y
square each x value and calculate sum
square each y value and calculate sum
multiply xy for each ps and calculate sum

2. work out r
3. calculated > critical = result is significant

Question 5

how to work out the df for pearson’s r?

Answer 5

N-2