Association Of Two Variables

Question 1

What are the 2 types of correlation coefficient?

Answer 1

1. Pearson’s correlation coefficient
2. Spearman’s correlation coefficient

Question 2

Correlation coefficient is represented as:

Answer 2

R= the strength of association, from -1 to +1

Question 3

How to test the correlation coefficient of 2 variables?

Answer 3

Null hypothesis, Ho: there is no linear association between variables
P-value: the probability that the variables are related
- p>0.05: accept null hypothesis, there is no relation between variables
-p<0.05: reject null hypothesis, there is a relation between variables

Question 4

Pearson’s correlation coefficient is used when..

Answer 4

• continuous vs continuous variable
• measures the effect of change in one variable when the other variable changes
• e.g. hypothesis: up until a certain age, a child’s height will keep increasing as his/her age increases

Question 5

Spearman’s correlation coefficient is used when..

Answer 5

• ordinal vs ordinal variable OR ordinal vs continuous variable
• e.g. hypothesis, students who do well in math will do well in science

Question 6

Chi-squared test

Answer 6

• tests if 2 categorical variables are related in a population
• null hypothesis, Ho: there is no association between the variables
• usually involves tabulated data in rows and columns
• nominal vs nominal variable OR nominal vs ordinal variable
• e.g. hypothesis: education level and marital status are related in SG