Curriculum
Statistics — Third Secondary
Unit 1: Correlation and Regression
0/4
Unit 2: Advanced Statistical Measures
0/2
Unit 3: Probability
0/2
Unit 4: Random Variables
0/4
Unit 5: The Normal Distribution
0/2
Text lesson
Correlation
Correlation
Pearson’s formula and how to calculate r
Pearson’s formula and how to calculate r
- The formula used in this course is:
- r = (n Σxy − Σx Σy) ÷ √[ (n Σx² − (Σx)²) × (n Σy² − (Σy)²) ]
- where n is the number of pairs, Σx is the sum of the x-values, Σy is the sum of the y-values, Σxy is the sum of the products of each pair, Σx² is the sum of the squares of the x-values, and (Σx)² is the square of the sum of the x-values.
- Make a table with columns x, y, xy, x² and y².
- Add each column to get Σx, Σy, Σxy, Σx² and Σy².
- Calculate the numerator (n Σxy − Σx Σy) first, then each part of the denominator separately.
- Divide the numerator by the square root. Check that the result lies between −1 and +1. If it does not, there is a calculation error.
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