Topic 15: Review Exercises 7.15 1. Platelets are an important part of the blood because they cause blood to clot when that is needed to stop bleeding. The drug eltrombopag (referred to as EL) , was tried on patients with chronic liver disease who were about to be operated on to see whether it would prevent the need for transfusion of platelets during the surgery and shortly thereafter. Read the following excerpt from the abstract that accompanied the study and answer the questions below. Method: platelet counts of less than 50,000 per cubic millimeter to receive EL, at a dose of 75mg daily or a placebo for 14 days before a planned elective invasive procedure that was performed within 5 days after the last dose. The primary end point was the avoidance of a platelet transfusion before, during, and up to 7 days after the procedure. " We randomly assigned 292 patients with chronic liver disease of diverse causes and Results: A platelet transfusion was avoided in 104 of 145 patients who received EL (72%) and in 28 of 147 who received a placebo (19%)." (a) Identify the subjects in the study. (b) Was this a controlled experiment or an observational study? Explain. Can cause and effect be inferred? (c) Do the sample percentages suggest that the drug was effective in reducing the chance of needing platelet transfusions? (d) What are the treatments? 2. Assume that the length of human forearms is symmetric, unimodal and bell-shaped with mean 12in. and standard deviation 3.25in. (a) What percentage of humans would have forearm length between 8.75in and 18.5in? (b) What is the 16th percentile for forearm length? (c) If Kevin Durant has forearms that are 20in long, would he be considered an outlier? 3. Data was collected on the weight of trash in a household (in lbs.) and the number of people in the household. The equation of the linear relationship between the variables is given as Trash = 2.34 + 11.30(People) (a) Interpret the slope of the regression line in terms of the problem. (b) Predict the weight of trash in a household of 5 people. r D0.877, find the proportion of variation in the weight of %3D trash based on its linear relationship with the number of people in the household. Does this value make you comfortable making predictions? dong