Examples -the goodness-of-fit test and independence test_1

# Examples -the goodness-of-fit test and independence test_1...

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The Chi-square Goodness-of-fit test Example A gift shop owner states that 45% of customers only do window shopping, 35% of customers buy one item and 20% of customers buy two or more items. In a randomly selected week, 95 customers bought nothing, 75 customers bought one item and 30 customers bought two or more. Is the distribution of customers in that week is the same as that stated by the gift shop owner? (Use α = 0.05) ______________________________________________________________ Number observed Expected Square of Chi-Square Of items frequency frequency Difference difference subtotal O E O - E (O - E) 2 (O - E) 2 /E 0 . 1 . 2 or more .

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The Chi-Square independence test A study of 531 persons injured in bicycle crashes was conducted and resulted in the following contingency table: Helmet Worn No Helmet Total Facial injuries received 30 182 212 All injuries nonfacial 83 236 319 Total 113 418 531 (a) At the 5% significance level, do the data provide sufficient evidence to conclude that an association exists between facial injuries and wearing a helmet?
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