Question

Is there an association between the use of a computerized system and hospital mortality? In a large-scale hospital study, the study investigator randomly sampled 35 hospitals from all hospitals in Texas. Within each of the sampled hospitals, 500 patients who were hospitalized during the past year were randomly chosen. Their medical records were retrieved and whether they died while hospitalized was noted. It was found that on average, hospitals (26 of them) in which health care information is gathered and stored on computers had a lower patient death rate than hospitals (9 of them) that still rely on the 'paper' system (using paper forms and handwritten notes).

1) What kind of study is this?

A. An experiment

B. An observational study

C. None of the above

2) What sampling method was employed in selecting the 17500 patients?

A. Multistage sampling

B. Simple random sampling

C. Systematic sampling

D. Stratified random sampling

E. None of the above

3) Which of the following is the population of interest to the study investigator? Choose the most appropriate answer.

A. All patients who were admitted to the 35 selected hospitals in Texas

B. All hospitals in Texas

C. The 35 Texas hospitals that were selected in the study

D. The 17500 patients whose medical records were retrieved in the study

E. None of the above

4) Which of the following statements is correct about the average patient death rate of all Texas hospitals in which health care information is gathered and stored on computers?

A. It is a parameter.

B. It is a statistic.

C. It is a variable of interest.

D. None of the above

5) What graphical display is appropriate for comparing the distribution of patient death rates between hospitals that use computer systems and those that rely on the paper system?

A. A stem-and-leaf display

B. A scatterplot

C. A bar chart

D. Side-by-side boxplots.

6) Mr. Prudence read about the study results and concluded from there that hospitals should adopt computerized automation of notes and records because it increases patients' chance of survival. Which of the following is a correct statement about Mr. Prudence's conclusion?

A. It is a valid conclusion because the study was based on a very large number of patients.

B. It is a valid conclusion because the study results showed that hospitals which use computerized systems have a lower patient death rate.

C. It is an invalid conclusion because this study does not necessarily prove a causal relationship between the use of a computerized system and hospital mortality.

D. Both A) and B)

Answer 1

(1)

This is an observational study because here the variables are not controlled in any way, they are just analyzed without being subject to any sort of control conditions.

(2)

This is a multistage sampling method, because first the 35 hospitals were randomly chosen from all hospitals, which forms the first stage.

In the next stage, 500 patients were randomly selected from each hospital, which forms the second stage of random sampling.

(3)

The population of interest is all the hospitals in Texas, because here the aim is to see if use of computer system in a hospital improves the mortality rate. So the focus is on the hospitals.

(4)

Since this is a characteristic of the population, so it is a parameter.

(5)

A bar chart would be a very good option because we simply want to compare the average death rates between the two categories of hospitals, so there is only one parameter that needs to be compared.

(6)

The correct option is:

C. It is an invalid conclusion because this study does not necessarily prove a causal relationship between the use of a computerized system and hospital mortality.

This is because although the data is suggestive of this, but we have not done a hypothesis test to determine the significance of this result.