Please use SAS to solve these questions and provide the codes: Scientists examined subjects with chronic, nonspecific
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Please use SAS to solve these questions and provide the codes:
Scientists examined subjects with chronic, nonspecific low back pain. In this study, 20 of the subjects completed a survey questionnaire assessing physical functioning (Y) at baseline, and after 1, 3, and 6 months (time). Subjects also received two types of treatment (treat). Higher physical functioning values indicate better physical functioning.
- a. We first want to assess if there is a difference in treatments across time. Therefore, model physical functioning as a function of time (as a continuous variable), drug, time, and drug interaction, and adjust for age. You may use the compound symmetry correlation/covariance structure. Identify, test, and interpret the interaction term for time and drug.
- b. We now want to look at time as a categorical variable (baseline as the referent group). Rerun the model with time, drug, and age as the predictors but with NO interactions. Which correlation/covariance structure is best?
- c. Using the best correlation/covariance structure from part b), identify and test the hypothesis needed to determine if there is a difference in treatment, interpret your result. (Perform hypothesis testing and interpret).
Related Book For
Statistics The Art and Science of Learning from Data
ISBN: 978-0321755940
3rd edition
Authors: Alan Agresti, Christine A. Franklin
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