Stock returns
Companies that are ISO 9000 certified have met standards that ensure they have a quality management system committed to continuous improvement. Going through the certification process generally involves a substantial investment that includes the hiring of external auditors. A group of such auditors, wishing to "prove" that ISO 9000 certification pays off, randomly selected a sample
a) What was the purpose of using Major as a blocking factor?
b) Given the results, was it necessary to use Major as a blocking factor? Explain.
c) State the conclusion from this analysis.