Space Shuttle Challenger Disaster

On January 28, 1986 the space shuttle Challenger disintegrated 73 seconds after liftoff from Kennedy Space Center. The most disturbing part of the space shuttle Challenger disaster was that the O-ring failure had been foreseen by the manufacturer’s engineers, who were unable to convince managers to delay the launch. Providing a better analysis and visualization of the data could have helped improve the decision-making process and potentially built a stronger case for the engineers about the effect of cold weather on O-ring functionality.

Problems Fitting a Nonlinear Model Using Log-Transformation

Power-law relationships are one of the most common patterns in the environmental. This post presents an example of the problems that can occur when fitting a nonlinear model by transforming to linearity using natural logarithms.

Dixon’s Outlier Test

Dixon’s test is simple, easy to understand, and is widely used in the scientific community. Data recorded to some specific measurement increment can become a problem for outlier tests, such as Dixon’s test. Dixon’s test assumes that the data values (aside from those being tested as potential outliers) are normally distributed. Most sample distributions are not normally distributed.

Nonparametric Trend Analysis

Detection of temporal trends is one of the most important objectives of environmental monitoring. This post examines nonparametric temporal trend analysis using the Mann-Kendall test and the Theil-Sen regression estimator.

How Robust Is the Two-Sample T-Test?

The most common activity in research is the comparison of two groups. The t-test is robust to departures from normally for moderate tailed, symmetric distributions. When the data come from a heavy tailed distribution, even one that is symmetric, the two-sample t-test may not perform as designed.