Question

Question: Heart rate variability of police officers. Are police officers susceptible to higher-than-normal heart rates? The heart rate variability (HRV) of police officers was the subject of research published in the American Journal of Human Biology (January 2014). HRV is defined as the variation in time intervals between heartbeats. A measure of HRV was obtained for each in a sample of 355 Buffalo, N.Y., police officers. (The lower the measure of HRV, the more susceptible the officer is to cardiovascular disease.) For the 73 officers diagnosed with hypertension, a 95% confidence interval for the mean HRV was (4.1, 124.5). For the 282 officers who are not hypertensive, a 95% confidence interval for the mean HRV was (148.0, 192.6).

a. What confidence coefficient was used to generate the confidence intervals?

b. Give a practical interpretation of both 95% confidence intervals. Use the phrase “95% confident” in your answer.

c. When you say you are “95% confident,” what do you mean?

d. If you want to reduce the width of each confidence interval, should you use a smaller or larger confidence coefficient? Explain.

Short answer

Answer

1. 95%
2. 95% of the repeated samples taken will contain the population mean.
3. 95% of the times, one can be successful
4. No.

Step-by-step solution

Determining the confidence coefficient 

a.

The confidence coefficient is nothing but the exact level of confidence considered by the researcher. In this case, for conducting the test on the heart rate variability of 73 police officers is 95%.

Elucidation on practical interpretation

b. Suppose repeated samples are taken into consideration by the researchers in the research process, and the 95% confidence interval is computed for every sample separately. That time out of all the intervals, 95% of them would contain the population mean

Meaning of 95 percent confident 

When anybody says before attempting anything that he/she is 95% confident, it means that if the event occurs 100 times, then he/she can win 95 times. This is applicable in the research processes also by the researchers.