A data set from a study that examined the effect of a specific diet on blood pressure is below. Participants (n = 72) were randomly assigned either to a group that was put on the diet (Diet = Present) or to a group that was not put on the diet (Diet = Absent), and researchers wanted to know whether the diet had a significant impact on blood pressure. Evaluate the homogeneity of variance assumption for the test and report the results (i.e., is the assumption reasonable for this analysis/data set?). Biofeedback Drug Diet BldPres Present X Absent 170 Present X Absent 175 Present X Absent 165 Present X Absent 180 Present X Absent 160 Present X Absent 158 Present X Present 161 Present X Present 173 Present X Present 157 Present X Present 152 Present X Present 181 Present X Present 190 Present Y Absent 186 Present Y Absent 194 Present Y Absent 201 Present Y Absent 215 Present Y Absent 219 Present Y Absent 209 Present Y Present 164 Present Y Present 166 Present Y Present 159 Present Y Present 182 Present Y Present 187 Present Y Present 174 Present Z Absent 180 Present Z Absent 187 Present Z Absent 199 Present Z Absent 170 Present Z Absent 204 Present Z Absent 194 Present Z Present 162 Present Z Present 184 Present Z Present 183 Present Z Present 156 Present Z Present 180 Present Z Present 173 Absent X Absent 173 Absent X Absent 194 Absent X Absent 197 Absent X Absent 190 Absent X Absent 176 Absent X Absent 198 Absent X Present 164 Absent X Present 190 Absent X Present 169 Absent X Present 164 Absent X Present 176 Absent X Present 175 Absent Y Absent 189 Absent Y Absent 194 Absent Y Absent 217 Absent Y Absent 206 Absent Y Absent 199 Absent Y Absent 195 Absent Y Present 171 Absent Y Present 173 Absent Y Present 196 Absent Y Present 199 Absent Y Present 180 Absent Y Present 203 Absent Z Absent 202 Absent Z Absent 228 Absent Z Absent 190 Absent Z Absent 206 Absent Z Absent 224 Absent Z Absent 204 Absent Z Present 205 Absent Z Present 199 Absent Z Present 170 Absent Z Present 160 Absent Z Present 179 Absent Z Present 179

This research was conducted with Korean adolescents in the Los Angeles area. Would you be willing to generalize the results of this study to Korean adolescents who live in other regions of the country? Why or why not.

A drug which is used for treating diabetes has potentially dangerous side effects if it is taken in doses which are larger than the required dosage for the treatment. A medical researcher believes that the variance in dosage is different for two tablets made by different production facilities. The sample variance of a sample of 11 dosages of tablet "A" is 0.013 . The sample variance of a sample of 28 dosages of tablet "B" is 0.01 . Construct the 90% confidence interval for the ratio of the population variances. Round your answers to four decimal places.

A researcher is interested whether a new drug is effective in changing patients' cholesterol levels. She divided 33 patients into 3 groups according to the dosage the patient received. The cholesterol levels of all patients are measured and used as the data for the Analysis of Variance (ANOVA). If she reported the test statistic F = 2.1 What is the degree of freedom for the numerator of the F statistic? What is the degree of freedom for the denominator of the F statistic? What is the P-value of the F-test? (Round to 3 decimals) Given the significance level of 0.01, what can she conclude from the test? *The patients in differnt groups have simliar average cholesterial levels. The drug made no difference. *At least one group of patients have an average cholesterol level that is different from the other groups. The drug may have an effect.

What correctly represents the coefficient of determination in terms of the variance that is an output from the analysis of variance table?

Ritalin has been shown to increase attention span and improve academic performance in children with ADHD (Evans et al., 2001). To demonstrate the effectiveness of the drug, a researcher selects a sample of n = 20 children diagnosed with ADHD and measures each child’s attention span before and after taking the drug. The data show an average increase of attention span of MD = 4.8 minutes with a variance of s2 = 125 for the sample of difference scores.    Is this result sufficient to conclude that Ritalin significantly improves attention span? Use a one-tailed test at .05.    Compute the 80% confidence interval for the mean chance in attention span for the population.

An HIV clinical trial with 1151 subjects was conducted. We will focus on two variables from this trial: IVDrug and Age. IVDrug is a categorical variable that indicates whether each subject never, previously, or currently uses IV drugs. Age lists the subject's age in year. Thus, we have age for subjects in three treatment groups. Assume that the samples were collected independently and come from a normally distributed population with equal variances. An ANOVA is used to test whether average age in the three IV drug groups is the same. A partially filled-in ANOVA table is listed below. Use a significance level of 0.05. p-value Treatment Error Total df SS MS 76.77 F 7.5586