Andy Sleeper

Andy Sleeper is President of Successful Statistics LLC, where he provides customized training and consulting services to clients around the world. Sleeper has degrees in Electrical Engineering and Statistics, and is a licensed Professional Engineer. Sleeper has written two books, Design for Six Sigma Statistics and Six Sigma Distribution Modeling, both published by McGraw-Hill. He can be contacted at Andy@SuccessfulStatistics.com or at 970-420-0243.


The meeting was tense. After a splashy release, users have complained about the uPod music player. Vibration from jogging or dancing tends to lock up the uPod, requiring the user to remove and replace the battery. Bloggers have been ruthless, and this product is fast becoming a stinker for Durian Computer Company.The engineering team has...Full Article »
Keep things as simple as possible, but not simpler. – Albert Einstein (paraphrased) When I was a kid, my big sister drove a red 1967 VW Bug. In its day, this was an innovative car. It had 54 horsepower, a two-speed windshield wiper and zero computers. The heat was inadequate and it broke down a lot, but it got 100 miles per gallon...Full Article »
Confidence intervals are the most valuable statistical tools available to decision makers. However, for a variety of reasons, confidence intervals are not used as frequently as they should. This article answers two questions that are often misunderstood:Why are point estimates useless for making decisions?What is the best confidence level?This...Full Article »
Part 2—Fisher One-Sample Sign TestThis two-part article of this column presents two well-established statistical tools that are easy to remember. Part 1 discussed Tukey’s end count test, which identifies significant differences in the distribution of two samples. In Part 2, you will see how Fisher’s one-sample sign test can be...Full Article »
The ability to make the right decision quickly is essential in business. When decisions involve interpreting data, it is tempting to go with "gut feel" rather than wait for a statistician or a computer analysis. But what if you could quickly decide whether your data represents a significant effect, and state your confidence level, with no computer...Full Article »