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Example 158 Tech: Cardiac stents are used to open a closed artery in order to reduce the risks of a heart attack in at risk patients. Medical researchers are interested in determining if the length of time spent in the hospital after a patient undergoes the implantation of a cardiac stent is affected by the patient’s view from the hospital bed. The researchers randomly assigned 90 cardiac stent patients to one of three different types of hospital rooms for their recovery: a room with a view (V) of nature (trees, grass, and open sky), a room with pictures (P) of nature on the walls but no window view, or a room without a view (N) and without images of nature on the walls. To block out the effect of different surgeons, the researchers used patients from three different surgeons. The response variable of interest for the study was the length of hospital stay. Complete the ANOVA table below and use the results to answer the following questions:
a) Which variable represents the treatments in this experiment?
b) Which variable represents the blocks in this experiment?
c) What is the null hypothesis for a test of the treatment effect?
d) What is the p-value for the test of the treatment effect?
e) What is the decision regarding the null hypothesis for the test of the treatment effect?
f) Based on the results of this experiment, do people in these different room types all have the same average length of hospital stay?
g) At a 5% significance level, is the length of hospital stay affected by the choice of surgeon?
h) Use the results of the multiple comparison procedure, included with the SPSS output, to construct a diagram that ranks the means for our different room types from small to large.
i) Summarize your conclusions for this ANOVA RBD experiment. Be sure to state which means are significantly different from each other, if any.