Inference

To enter the Inference application, highlight the app using the directional keys. Press the ok key to enter the application. This app allows you to perform hypothesis tests and construct confidence intervals.

Getting started

The first screen of the application allows you to choose between Tests and Intervals.

Tests

This section allows you to perform hypothesis tests. The following types of tests are available:

• z-test for a proportion or the difference of two proportions
• t-test or z-test for a mean or the difference of two means
• t-test for a slope
• chi-square goodness-of-fit test or chi-square homogeneity/independence test

For each of these tests, the interface first allows you to define your null hypothesis and your alternative hypothesis (this step is implicit in the chi-square test). You then enter your sample data.

The calculator then calculates the test statistic and P-value. A graphical representation is also available with the P-value and rejection region shaded.

Intervals

This section is used to construct confidence intervals. The following types of intervals are available:

• z-interval for a proportion or the difference of two proportions
• t-interval or z-interval for a mean or the difference of two means
• t-interval for a slope

For each of these types of intervals, you are first prompted to enter sample data. The calculator then provides the critical value, standard error and margin of error. It also provides the endpoints of the interval as well as a visual representation.

You can then use the copy key to copy the calculated interval and paste it into another application.