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Unformatted text preview: STAT 8200 Design of Experiments for Research Workers Lab Due Friday, Sept. 10 Example: Zelazo et al. (1972) describe an experiment in which the age at which children first walked is studied. Newborn children were randomly placed into one of four treatment groups: active exercise, passive exercise, no exercise, or an 8-week control group. Infants in the active-exercise group received walking and placing stimulation four times a day for 8 weeks, infants in the passive-exercise group received an equal amount of gross motor stimulation, infants in the no-exercise group were tested along with the first two groups at weekly intervals, and the 8-week control group consisted of infants observed only at 8 weeks to control for possible effects of repeated examination. The resulting ages at first walking (in months) appear below. Active Passive No-exercise 8-week Group Group Group Control Group 9.00 11.00 11.50 13.25 9.50 10.00 12.00 11.50 9.75 10.00 9.00 12.00 10.00 11.75 11.50 13.50 13.00 10.50 13.25 11.50 9.50 15.00 13.00 These data also are contained in the file walking.sas which also contains a SAS program to analyze the data. Copy this file to your home directory, run it and examine the program and output. This experiment is an example of a one-way layout. There is a single treatment factor with four levels (the four groups) in a completely randomized design. An appropriate statistical model for these data is y ij = i + ij where y ij is the age at first walking for the j th child in the i th...
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This note was uploaded on 11/13/2011 for the course STAT 8200 taught by Professor Staff during the Fall '08 term at University of Georgia Athens.
- Fall '08