Companies that have a certain certification have met standards that ensure they have a quality management system committed to continuous improvement. In 2008, a group of auditors, wishing to "prove" that this certification pays off, randomly selected a sample of small and large companies with and without certification. Size was based on the number of employees. They computed the % change in closing stock price from August 2006 to August 2007. The two-way ANOVA results are shown in the accompanying table. Complete parts a through c. LOADING... Click the icon to view the ANOVA results. Question content area bottom Part 1 a) Is this an experiment or an observational study? A. An experiment with a randomized block design B. An experiment with a factorial design C. An observational study, or more specifically, a retrospective study D. An observational study, or more specifically, a prospective study Total DF Sum of Squares Mean Square F-ratio P-value ISO 9000 1 2667.3 2667.3 6.269 0.017 Size 1 0.4 0.4 0.001 0.975 Interaction 1 1496.4 1496.4 3.517 0.068 Error 36 16596.2 425.5 Total 39 20760.3