Pearson Edexcel IAL Mathematics S1.4.3 Product moment correlation

Practise calculating product moment correlation coefficients and interpreting their strength, direction and limitations in context.

Exam points

calculate r from Sxy, Sxx and Syy, giving the required degree of accuracy
interpret the sign and size of r in the context of the two variables
state whether r supports a linear model, using closeness to 1, -1 or 0

[Maximum number: 2]

A biologist is studying horses.

The biologist records the height, $h \mathrm{~cm}$ , and the weight, $w \mathrm{~kg}$ , of 8 horses.
The table below shows the biologist's results.

Table for Question S1.4.3 - Product moment correlation question 1 — Edexcel A-Level Mathematics AS

[You may use $\sum h=1160 \sum w=4160 \sum h w=604135 \sum w^{2}=2166600 \quad \mathrm{~S}_{h h}=286$ ]

Calculate the value of the product moment correlation coefficient between h and w

$r=\frac{935}{\sqrt{286\times3400}}=0.9481\ldots$
awrt 0.948
M1, A1

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S1.4.3 - Product moment correlation question 1