Helmet Sizes for New Zealand Airforce

Keywords: paired t test

Description

After purchasing a batch of flight helmets that did not fit the heads of many pilots, the NZ Airforce decided to mesure the headsizes of all recruits. Before this was carried out, information was collected to determine the feasibility of using cheap cardboard callipers to make the measurements, instead of metal ones which were expensive and uncomfortable. The data lists the head diameters of 18 recruits measured once using cardboard callipers and again using metal callipers. One question is whether there is any systematic difference between the two sets of callipers. One might also ask whether there is more variability in the cardboard callipers measurement than that of the metal callipers.

Download

Data file (text)

Source

Data courtesy of Dr Stephen Legg.

Seber and Lee (1998). Page 545.