Peak expiratory flow (PEF)
Question
Peak expiratory flow (PEF) is a measure of a patient’s ability to expel air from the lungs. Patients with
asthma or other respiratory conditions often have restricted PEF. The mean PEF for children free of asthma is 306. An investigator wants to test whether children with chronic bronchitis have restricted PEF. A sample of 40 children with chronic bronchitis are studied and their mean PEF is 279 with a standard deviation of 71. Is there statistical evidence of a lower mean PEF in children with chronic bronchitis? Run the appropriate test at .05.
1. Calculate Critical Z value:
2. Calculate Computed Z:
3. Based on comparing the critical z value to the computed z value, which of the following is (are) true?