• Check the assumptions for a two-sample [latex]t[/latex] confidence interval for population mean.
• Calculate and explain a confidence interval for the difference between two population means.

Confidence Interval: estimate [latex]\pm[/latex] margin of error

Cell Phones while Driving

Previously, we used data from a study investigating how driving while using a cell phone affects reaction time.^[1] In this study, [latex]64[/latex] students were randomly assigned to one of two groups. Students in both groups were asked to drive in a driving simulator and to press a brake button as quickly as possible when they saw a red light. Response times (in milliseconds) were measured. Students in one group used their cell phones while driving in the simulator, and students in the other group did not use their cell phones.

Let’s use the data to estimate the difference between the mean reaction time for people who use their cell phones while driving and the mean reaction time for people who do not use their cell phones while driving.

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