OCR Further Statistics AS 2024 June — Question 5

Exam BoardOCR
ModuleFurther Statistics AS (Further Statistics AS)
Year2024
SessionJune
TopicHypothesis test of Spearman’s rank correlation coefficien

5 In a fashion competition, two judges gave marks to a large number of contestants. The value of Spearman's rank correlation coefficient, \(\mathrm { r } _ { \mathrm { s } }\), between the marks given to 7 randomly chosen contestants is \(\frac { 27 } { 28 }\).
  1. An excerpt from the table of critical values of \(\mathrm { r } _ { \mathrm { s } }\) is shown below. \section*{Critical values of Spearman's rank correlation coefficient}
    1-tail test5\%2.5\%1\%0.5\%
    2-tail test10\%5\%2\%1\%
    \multirow{3}{*}{\(n\)}60.82860.88570.94291.0000
    70.71430.78570.89290.9286
    80.64290.73810.83330.8810
    Test whether there is evidence, at the 1\% significance level, that the judges agree with each another. The marks given by the two judges to the 7 randomly chosen contestants were as follows, where \(x\) is an integer.
    ContestantABCD\(E\)\(F\)G
    Judge 164656778798086
    Judge 2616378808190\(x\)
  2. Use the value \(\mathrm { r } _ { \mathrm { s } } = \frac { 27 } { 28 }\) to determine the range of possible values of \(x\).
  3. Give a reason why it might be preferable to use the product moment correlation coefficient rather than Spearman's rank correlation coefficient in this context.