Melanoma treatment. An experimentevaluated the use of genetically engineered white blood cells inthe treatment of patients with melanoma.y Patients weredivided into three cohorts. Patient cohort 1 received geneticallyengineered lymphocytes that were cultured ex vivo for 19days. Cohort 2 received cells that were cultured for between 6 and9 days. Cohort 3 received cells that were generated by a secondrapid expansion performing after 8 to 9 days. Cell doubling timeswere as follows.
Cohort1Â Â Â Â Â Â Â Â Â Â Â Â Â Â 8.7Â Â Â Â Â Â Â Â Â 11.9Â Â Â Â Â Â Â 10.0
Cohort 2Â Â Â Â Â Â Â Â Â Â Â Â Â 11.4Â Â Â Â Â Â Â 1.0Â Â Â Â Â Â Â Â Â 1.3Â Â Â Â Â Â Â Â Â 1.0Â Â Â Â Â Â Â Â Â 2.0Â Â Â Â Â Â Â Â Â 0.6Â Â Â Â Â Â Â Â Â 0.8Â Â Â Â Â Â Â Â Â 0.7Â Â Â Â Â Â Â Â Â 0.9Â Â Â Â Â Â Â Â Â 1.9
Cohort 3Â Â Â Â Â Â Â Â Â Â Â Â Â 0.9Â Â Â Â Â Â Â Â Â 3.3Â Â Â Â Â Â Â Â Â 1.2Â Â Â Â Â Â Â Â Â 1.1
Either create a file with these data or download the fileMORGAN2006.* from the companion website. Most statistical programsrequire you to enter that data into two columns: one column for theexplanatory variable (COHORT) and the other for the responsevariable (DOUBLING). Your final data table should have 2 columnsand 18 rows.
If you do not have access to a statistical program, considerusing BrightStat. com.z Use of BrightStat.com is free.However, you must register as a user in order to access its ANOVAfeatures.
(a)   Calculate the means, standard deviations,and sample sizes of each group. Use the “double the standarddeviation†benchmark to assess whether group variances aresignificantly different. Is there evidence ofheteroscedasticity?
(b)   Conduct Levene’s test for unequal variance.Show all hypothesis testing steps. What do you conclude?
