In which conditions, Karl Pearson's correlation coefficient can be calculated?
1.If means of both the variables are equal
2.If one variable is measured in interval scale and another is measured in ordinal scale
3.If there is linear relationship between two variables
4.If data are obtained in interval or ratio scale for both the variables
5.If direction of relationship between two variables is known
A3 & 4 only ✓ Correct
B3, 4 & 5 only
C2, 4 & 5 only
D1, 3 & 5 only
Correct answer: (A) 3 & 4 only
Explanation
Karl Pearson's correlation can be computed when there is a linear relationship between the two variables and both are measured on an interval or ratio scale, so statements 3 and 4 apply.
Equal means of the two variables is not a requirement for Pearson correlation.
Measuring one variable on interval and the other on ordinal scale suits rank correlation, not Pearson.
Prior knowledge of the direction of the relationship is not a precondition.
Pearson r measures the strength and direction of a linear association.
For purely ordinal data Spearman rank correlation is used instead.
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