# Main Page

### From Math

Scratchings about math by JoDu and friends

## Contents

# Science

Trying to use this like an open notebook now.

My first effort is a Global cascade model

# Statistics

- Multivariate confidence explores how it is possible to have a predictor with large confidence intervals, but also a large best-guess effect. This is part of our standard cautionary tale about accepting the null hypothesis
- Logistic modeling in R; not very much here (yet).
- Permutation tests
- Centering -- questions about estimating main effects in the presence of interactions

# Dynamics

- SIR time scales: an intuitive exploration of the $2\pi \sqrt{AD}$ result
- The final-size argument: calculating the final size of simple epidemics.
- Pseudo-Erlang distributions: We should not be constrained by discrete values of the CV when making "boxcar" models

# Recreation

- Door lock: a nice, slightly mysterious result about the number of possible combinations on a door lock.
- Suitcase lock: a fun puzzle from Missouri State University's Challenge Problem Page
- Curving a test
- Nomogram: a graph that can do math. This nomogram solves simple quadratic equations.
- Harold's Saxon army