# Categorical Methods

• ### DAU StatRefresher: Probability

These tutorials on probability cover basic probability, random variables, expectations, and distributions with interactive assessment at the end of each tutorial.
• ### Exploratory Data Analysis (Engineering Statistics Handbook)

This chapter of the NIST Engineering Statistics handbook describes Exploratory Data Analysis with an introduction, a discussion of the assumptions, a description of the techniques used, and a set of case studies.
• ### Measurement Process Characterization Case Studies (Engineering Statistics Handbook)

This part of the NIST Engineering Statistics handbook contains case studies for the measurement process chapter.
• ### Relative Risks and Odd Ratios

This site provides a PowerPoint presentation of a lesson and examples of relative risks and odds ratios.
• ### Sampling Bias and The California Recall

This lesson deals with the statistics of political polls and ideas like sampling, bias, graphing, and measures of location. As quoted on the site, "Upon completing this lesson, students will be able to identify and differentiate between types of political samples, as well as select and use statistical and visual representations to describe a list of data. Furthermore, students will be able to identify sources of bias in samples and find ways of reducing and eliminating sampling bias." A link to a related worksheet is included.
• ### Virtual Statistician

This site contains lessons which include steps, examples, and a calculator, on standard deviation, Pearson's r, t-test, one-way ANOVA, and Tukey's Post Hoc Test.
• ### Point Estimation

This online, interactive lesson on point estimation provides examples, exercises, and applets concerning estimators, method of moments, maximum likelihood, Bayes estimators, best unbiased estimators, and sufficient, complete and ancillary statistics.
• ### Hypothesis Testing

This online, interactive lesson on hypothesis testing provides examples, exercises, and applets which includes tests in the normal model, Bernoulli Model, and two-sample normal model as well as likelihood ratio and goodness of fit tests.

• ### Resampling Statistics: Randomization and the Bootstrap

This set of pages describes software the author wrote to implement bootstrap and resampling procedures. It also contains an introduction to resampling and the bootstrap; and examples applying these procedures to the mean, the median, correlation between two groups, and analysis of variance.
• ### Resampling methods: Concepts, Applications, and Justification

This journal article is a summary of resampling methods such as the jackknife, bootstrap, and permutation tests. It summarizes the tests, describes various software to perform the tests, and has a list of references.