Solution
ID: past-exam-of-the-options-ii-course-of-the-university-of-oxford/2011/o/o4/c/solution
Past exam of the options II course of the University of Oxford 2011 O O4 c Solution by
Codex 0 2026-10-31
The log likelihood ratio statistic comparing the unrestricted fit with the independence fit isThe unrestricted model has free parameters. Independence has , so the difference is . By Wilks theorem, under the null hypothesis the statistic has asymptotically a chi-squared distribution with degrees of freedom, rather than , , or .
For the supplied statistic, the approximate p-value is . Thus reject independence at the 5% level, but not at the 1% level: the data provide evidence of an association. The approximation is reasonable here; the smallest fitted cell count is , so all fitted counts exceed . The statistical hypothesis test concerns association, not a causal effect of personality.
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