OCR Stats 1 2018 September — Question 11

Exam BoardOCR
ModuleStats 1 (Statistics 1)
Year2018
SessionSeptember
TopicHypothesis test of Pearson’s product-moment correlation coefficient

11 In an experiment involving a bivariate distribution ( \(X , Y\) ) a random sample of 7 pairs of values was obtained and Pearson's product-moment correlation coefficient \(r\) was calculated for these values.
  1. The value of \(r\) was found to be 0.894 . Use the table below to test, at the \(5 \%\) significance level, whether there is positive linear correlation in the population, stating your hypotheses and conclusion clearly.
    1-tail test 2-tail test5\%2.5\%1\%0.5\%
    10\%5\%2\%1\%
    \(n\)
    1----
    2----
    30.98770.99690.99950.9999
    40.90000.95000.98000.9900
    50.80540.87830.93430.9587
    60.72930.81140.88220.9587
    70.66940.75450.83290.9745
    80.62150.70670.78870.8343
    90.58820.66640.74980.7977
    100.54940.63190.71550.7646
    Scatter diagrams for four sets of bivariate data, are shown. \begin{figure}[h]
    \includegraphics[alt={},max width=\textwidth]{85de9a39-f8be-40ee-b0c8-e2e632be93d8-8_380_371_301_191} \captionsetup{labelformat=empty} \caption{Diagram A}
    \end{figure} \begin{figure}[h]
    \includegraphics[alt={},max width=\textwidth]{85de9a39-f8be-40ee-b0c8-e2e632be93d8-8_373_373_301_628} \captionsetup{labelformat=empty} \caption{Diagram B}
    \end{figure} \begin{figure}[h]
    \includegraphics[alt={},max width=\textwidth]{85de9a39-f8be-40ee-b0c8-e2e632be93d8-8_378_373_301_1064} \captionsetup{labelformat=empty} \caption{Diagram C}
    \end{figure} \begin{figure}[h]
    \includegraphics[alt={},max width=\textwidth]{85de9a39-f8be-40ee-b0c8-e2e632be93d8-8_378_373_301_1503} \captionsetup{labelformat=empty} \caption{Diagram D}
    \end{figure} It is given that \(r = 0.894\) for one of these diagrams.
  2. For each of the other diagrams, state how you can tell that \(r \neq 0.894\).