Descriptive Statisticss

The information provided from the Department of Transformation Statistics communicates the delays in departure and arrival for its passengers on a specific day in 2015. One would assume a relationship between late departures equating late arrivals. Finding the appropriate measure of center, the appropriate measure of variation, and using the suitable graph(s) needed to appropriately describe the data can help to illustrate the relationship between the two, and provide information regarding the frequency of occurrences.

For the DTS information provided, a scatterplot would best describe the relationship between arrival and departure delays because the two variables are quantitative (Moore, McCabe, & Craig, 2014). By using a smooth curve, it is possible to see that it is very close to a straight line, confirming the initial impression that the relationship between delays is approximately linear in nature (Appendix 1). This is due to the fact that if a mode of transportation is late to pick up passengers, it will likely be late to arrive at the destination, and if it is early to pick up, it will likely be early to drop off.

The median is best used as an appropriate measure of center because it is less affected by outliers. On the day the data was collected, the median departure delay was 3 minutes early, represented by -3 (Appendix 2). The median arrival delay was -5, or 5 minutes early (Appendix 3). As expected, the medians are close to each other.

References

Department of Transportation Statistics. (2015). Office of the Assistant Secretary for Research and Technology. Bureau of Transportation Statistics. Accessed from: http://transtats.bts.gov/DL_SelectFields.asp?Table_ID=236&DB_Short_Name=On-Time

Moore, D., McCabe, G., & Craig, B. (2014). Introduction to the Practice of Statistics, Eighth Edition. New York, NY: W.H. Freeman and Company