The following table is based on samples of patients diagnosed with gastric cancer, peptic ulcer, and controls from the same health maintenance operation. From the following table, test whether there...

The following table is based on samples of patients diagnosed with gastric cancer, peptic ulcer, and controls from the same health maintenance operation. From the following table, test whether there are significant differences in blood type among the three groups.

Workers were classified as having no (n = 949), mild (n = 44), moderate (n = 13), or severe heart failure (n = 1). Researchers want to compare these results with information on job history using a chi-square test. What do you suggest they do first before performing a chi-square test?