10. Rugby Injuries The prevalence and patterns of knee injuries among women collegiate rugby players were investigated using a sample questionnaire, to which 42 rugby clubs responded.19 A total of 76 knee injuries were classified by type as well as the position (forward or back)

of the player

a. Use the MINITAB printout to determine whether there is a difference in the distribution of injury types for rugby backs and forwards. Have any of the assumptions necessary for the chi-square test been violated?
What effect will this have on the magnitude of the test statistic?

b. The investigators report a significant difference in the proportion of MCL tears for the two positions (P , .05) and a significant difference in the proportion of ACL tears (P , .05), but indicate that all other injuries occur with equal frequency for the two positions. Do you agree with those conclusions?
Explain.

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Type of Knee Injury Meniscal MCL ACL Patella PCL Position Tear Tear Tear Dislocation Tear Forward 13 14 7 3 1 Back 12 9 14 2 1 Chi-Square Test for Association: Position, Injury Rows: Position Columns: Injury Meniscal Tear MCL Tear ACL Tear Patella PCL Tear All Forward 13 14 7 3 12.50 11.50 10.50 2.50 1 38 1.00 Back 12 9 14 2 1 38 12.50 11.50 10.50 2.50 1.00 All 25 23 21 5 2 76 Cell Contents Count Expected count Chi-Square Test Chi-Square DF P-Value Pearson 3.660 4 0.454 Likelihood Ratio 3.716 4 0.446 4 cell(s) with expected counts less than 5.