# Excel Workbooks

Unsupported and largely obsolete, but interesting examples of how powerful Excel can be for real analysis. All of these workbooks come as-is. For the most part, their functionality is straightforward, and if you have a need to use them, you should be able to figure out how to use them.

- Excel data analysis - This file contains an extensive set of macros for performing a variety of multivariate statistical analyses and data manipulation functions. Includes factor analysis, correlations, regression, cluster analysis, data smoothing, mean comparisons, descriptive statistics, using both weighted and unweighted and hierarchical data.
- IRT Information-based item selection - Illustrates the additive property of Fisher's information functions and the optimal selection of items in an IRT framework.
- Scatterplot ellipse - Demonstrates how to create a scatterplot ellipse to summarize a linear relationship graphically. It also good for illustrating outliers to a bivariate relationship.
- Estimates proficiency level thresholds and classify items - Using a set of item response parameters and codings, this workbook will find optimal cutpoints for proficiency levels on the latent continuum based on the percentage of tasks required for mastery of each proficiency level.