- Complete a two-sample [latex]t[/latex]-test for dependent population means from hypotheses to conclusions
Dependent Samples vs. Independent Samples
Previously, you learned how to create confidence intervals and conduct hypothesis tests with a single variable. You also learned how to compare means or proportions from two samples. Some statistical studies use samples from more than one population. In order to compare the difference between two populations, it is important to identify if the samples are dependent (paired) or independent. Dependent and independent sample hypothesis tests are used to answer questions about the difference between two population means.
In contrast, when samples are independently selected, the same variable is measured for both samples, but there is no logical way to pair an observation from one sample with a particular observation from the other sample.
Do not use your cell phone while driving!
The study in this in-class activity uses a single group of participants and measures their reaction times (in milliseconds) while performing a driving task without using their cell phones and then again while using their cell phones.[1]
The data collected include the reaction times (in milliseconds) with and without the use of cell phones for [latex]32[/latex] randomly selected participants. Therefore, each participant will have two reaction times, one for using a cell phone while driving and another for not using a cell phone while driving.
- Strayer, D. L. & Johnston, W. A. (2001, November 1). Driven to distraction: Dual-task studies of simulated driving and conversing on a cellular telephone. Psychological Science, 12(6), 462–466. DOI: 10.1111/1467-9280.00386 ↵