An environmental study measures the nitrogen concentration, xxx mg/L, and the dissolved oxygen level, yyy mg/L, at 15 different sites along an industrial canal. The data are summarised as follows:
Sxx=2 400S_{xx} = 2\,400Sxx=2400 ∑y=1 020\sum y = 1\,020∑y=1020 ∑y2=72 400\sum y^2 = 72\,400∑y2=72400 Sxy=−1 950S_{xy} = -1\,950Sxy=−1950
Determine the value of SyyS_{yy}Syy.
Calculate the product moment correlation coefficient for these data, giving your answer to 3 significant figures.
Interpret the value of the correlation coefficient in the context of the study.
A scientist converts the nitrogen concentration into grams per litre, www, such that w=x1000w = \frac{x}{1000}w=1000x.
State the value of SwwS_{ww}Sww.
State the value of the product moment correlation coefficient between www and yyy.
108 exam-style questions on Edexcel A Level Maths 1.2 Measuring Correlation. Each one has a worked solution and a mark scheme showing where the marks go.