Module 8 Assignment

NOTE: This assignment reinforces content on confidence intervals so you may find it helpful to refer back to the Module 7 content.  

We want to find out if being a top level manager (executive) at a large firm is associated with higher blood pressure. Assume that we are able to randomly select 100 individuals out of all the corporate executives of firms with over 200 employees. We want to be able to make a confidence statement about that population’s blood pressure.

a. Identify the population of interest and the sample.

b. Assume that the average systolic blood pressure for these 100 individuals is 140. Is 140 a statistic or a parameter? How do you know?

c. Assume that the population standard deviation for systolic blood pressure is 20. Calculate the standard error (see formula below) based on a standard deviation of 20 and a sample size 100. (Note: The symbol on the left side of the equation represents "standard error" or the "standard deviation of the sampling mean").

d. Using the formula from class (and showing your work or describing the process) calculate the 95% confidence interval (you can refer to the bottom of page 380 for the formula – remember that z=1.96 when we are calculating the 95% confidence interval). What is the lower confidence limit (LCL) and upper confidence limit (UCL) of our estimate?

e. Using the results from d, fill in the blanks in the following confidence statement:

Based on our sample of 100 corporate executives of firms with over 200 employees, we can be 95 certain, that the true population average systolic blood pressure for this population is ________+/-_________