Researchers recruited pregnant women diagnosed with gum disease who had refused dental treatment because of their pregnancy. The women were randomly assigned to either rinse with mouthwash daily (n=71) or not (n = 155) to see if this simple remedy could help delay the progression of gum disease. The number of bleeding sites on the gum of each subject was recorded at baseline and again 6 months later (mean = stdev below) Difference from baseline Baseline Month 6 Variable No. of bleeding sites, per subject Rinse Controls 58.7 +27.7 62.0 - 28.8 49.7 +28.0 77.2 + 25.0 +3.3 + 16.1 +27.5 + 20.0 D To see if there is evidence that gum disease worsens after 6 months in the population of pregnant women with untreated gum disease and not using a mouthwash, which inference procedure should be used?
a) one sample or matched-pairst procedure for a mean
b) two samplet procedure for two means
c) chi-square for two-way tables
d) ANOVA for several means
e) chi-square for goodness of fit D