HCAD 5220 Fall 2015 Ed Schumacher Homework 4 (Due September 22) 1. Suppose we are provided with the following information concerning the time required to perform two different services: Service A: Sample size=12, 𝑥̅ = 14.5, s=3.90 Service B: Sample size=12, 𝑥̅ = 22.0, s=5.39 a. Test at the level of significance =.05 whether it is reasonable to assume that the two samples came from populations having the same variance. b. Using the p-value, test at the level of significance =.05 whether the mean time required for service B is greater than for service A. Be sure to provide an interpretation of the p-value. 2. At BigCounty Community Hospital the administrator has implemented multiple innovations to attempt to reduce overall length of stay in the hospital. You have been asked to assess if these efforts have been successful. The Excel file titled Homework 4.xlsx, the work sheet “Big_Hospital_Data.xlsx” contains data on a sample of patients for 2012 and 2014. a) What is the overall average LOS in 2012 and in 2014? Is there evidence for decreased LOS? b) Is there evidence that LOS decreased within DRG? 3. One of the more frustrating problems plaguing hospitals and laboratories is the rate with which bacteria external to the patient contaminate blood cultures. Blood culture contaminations extend hospital stays and increase the cost of care. One of the keys to preventing infections is using proper specimen collection technique. Profiteering Community Hospital (PCH) is worried about their contamination rate and has taken steps to try to reduce it. They established a program to more fully standardize the collection process to ensure that all collections were done using the same technique. They are now interested to know if this program has reduced the infection rate. PCH collected data on blood samples taken in their hospital over two periods. Those in Period 1 were specimens collected prior to implementation and those in Period 2 were collected post implementation. These data are shown in the “Profiteering” worksheet in the Homework 4.xslx file. The file contains the following variables Period – 1=pre, 2=post Unit – which floor the specimen was collected (a, b, c, d, or ed, where ed is the emergency department and a, b, c, and d are other units.) Collected by – the type of clinician collecting the blood (Patient Care Partner, RN-Emergency, RN-Inpatient, other) Contaminated – yes or no a) Calculate the number of hours it takes to complete each collection. Is there evidence that registered nurses are faster than the other groups at collecting the specimens? b) What is the average infection rate in the pre-program period and in the after program period? Is there evidence that the hospital successfully reduced their infection rate? c) For those observations in Period 2, is there evidence of a difference in the infection rate for those collections starting before 6:00pm and those starting after 6pm? d) Are nurses significantly better at collecting specimen than the other groups? e) Is there a relationship between contaminations and the type of clinician collecting the specimen?