doctor used to believe that babies were equally likely to be born any day of the week, but with the rise in scheduled deliveries, the doctor now claims that babies are twice as likely to be born on a weekday (Monday through Friday) than on a weekend (Saturday and Sunday). She decides to test: Ha: Not all of the pi’s are as stated. She selects a random sample of 120 babies born this year and determines on which day of the week they were born. She finds that 4 were born on Sunday, 24 on Monday, 21 on
A doctor used to believe that babies were equally likely to be born any day of the week, but with the rise in scheduled deliveries, the doctor now claims that babies are twice as likely to be born on a weekday (Monday through Friday) than on a weekend (Saturday and Sunday). She decides to test:
Ha: Not all of the pi’s are as stated.
She selects a random sample of 120 babies born this year and determines on which day of the week they were born. She finds that 4 were born on Sunday, 24 on Monday, 21 on Tuesday, 18 on Wednesday, 22 on Thursday, 28 on Friday, and 3 on Saturday. The chi-square test statistic for goodness of fit is χ2 = 12.95 and the P-value is between 0.025 and 0.05.
The doctor had hypothesized that babies are twice as likely to be born on a weekday (Monday through Friday) than on a weekend (Saturday and Sunday). Because the P-value is less than 0.05 the doctor rejects the null hypothesis. She completes a follow-up analysis. Here is a table of the observed counts, the expected counts, and the components of the chi-square test statistic:
Based upon the follow-up analysis, why was the null hypothesis rejected?
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