BA 3300 Example 2 Hospital LOS


1) Can we conclude with 95% confidence that the average hospital Length of stay (LOS) is reduced from 5.0 days following administrative changes ?

data for a relatively large (>30) sample of 100 recent patients is provided in  CXA08_04.PRN

1) Data conversion

Data is provided as ASCII files. import the data into EXCEL sheets.

2) Generate descriptive statistics (with 90% CL)

3) Generate a histogram for the LOS data

4) Use a t test to test the hypotheses:

State null and Alternative (that's what the "A" stands for in Ha) Use Alpha=0.05 for all these tests, Hypothesized difference is 0
  • Is it okay to use t instead of Z for the LOS case even though the sample is large? why or why not?
  • use excel to generate appropriate P values for the observed T's. What do these mean? What do you conclude?
  • 5) Discussion:

  • Refer to the descriptive statistics, the histograms, and the P values.
  • Why do we use standard error instead of standard deviation in calculation of t values?
  • What do the "critical t values" mean?
  • What are your conclusions?
  • What are at least three things you could do to improve ability to detect differences between the hypothesized values and reality?