30.1 Introduction: Reaction times

A study (Strayer and Johnston 2001), examined the reaction times of students while driving.

In one study, two different groups of students were used: one group used a mobile phone, and a different group did not use a mobile phone. Their reaction times were measured in a driving simulator. These data were seen previously in Sect. 24.1.

The two groups receive different treatments: one group used a mobile phone while driving, and a different group did not use a mobile phone while driving.

The data are not paired; instead, the means of two separate (or independent) samples are being compared. (The data would be paired if each student was measured twice: once using a phone, and once without using a phone.)

Consider the RQ:

For students, is there a difference between the mean reaction time while driving, between students who are using a mobile phone and students who are not using a mobile phone?

The data are shown below.


Strayer DL, Johnston WA. Driven to distraction: Dual-task studies of simulated driving and conversing on a cellular telephone. Psychological Science. 2001;12(6):462–6.