Goodness of Fit Test Procedure
Goodness of fit tests compare observed frequencies O to expected frequencies E under a hypothesized distribution using χ² = Σ[(O - E)² / E]. If χ² exceeds the critical value, reject H₀ (the hypothesized distribution) at the specified significance level.
Real World
Transport for London tested whether bus arrival gaps at a stop followed an exponential distribution by grouping observed waiting times and comparing them to expected frequencies.
Exam Focus
Merge cells until all expected frequencies are ≥5 before calculating χ²; failing to do this loses marks on procedure questions.
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