Question

2. The Design of Research

A dataset consists of observations on flight departure times for airplanes at LaGuardia Airport during May and June of 2009. Data were collected on the following variables for 4029 flights:

Airline Carrier: American Airlines (AA) or United Airlines (UA)

Flight Delay: the number of minutes of delay for a given flight, such that

Number of minutes < 0, flight left early (category =

Number of minutes = 0, flight left on time

Number of minutes > 0, flight left late.

(a) What kind of variable is Airline Carrier?

(b) Is this an observational study or a designed experiment?

(c) After a careful analysis of the data, you find that on-time departures are more common for United Airlines. Is it reasonable to conclude that pre-flight procedures at United Airlines cause more on-time departures at LaGuardia Airport during the study period? Why or why not? If not, speculate and describe a confounding variable that might be responsible for the results. (3-4 sentences maximum.)

Answer 1

(a) The Airline Carrier is a categorical variable which two categories as American Airlines and United Airlines

(b) This is an observational study because there is no treatment assigned and the data would be collected based on what is seen.

(c) No, it is not reasonable to conclude that only pre-flight procedures at United Airlines cause more on-time departures at LaGuardia Airport during the study period because the pre-flight procedures are important but what important is the traveler’s arrival, if the travelers arrive on time then there will be more on-time departures.