Airlines strive to have flights arrive on time. Transportation statistics (www.transtats.bts.gov/Timeseries.asp) report the percentage of scheduled flights arriving on time in each month. We have data for 2005€“2010. Flights can fail to be on time for a variety of reasons, but do the on-time rates vary by month? We performed an ANOVA. The partially completed Analysis of Variance table is shown here.

a) Is this an experimental or observational study? Explain.
b) Is this a prospective or retrospective study? Explain.
c) State the null and alternative hypotheses.
d) Calculate the F-statistic.
e) The P-value for this statistic turns out to be

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Sum of Mean Source DF Squares Square F-ratio P-value Month 1047.92 Error 59 839.450 Tota 70 1887.37