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The Relationship Between Binge Drinking and COVID-19 Cases May Be Linear, But…

NOTE: This blog post has apparently been living rent-free in Dr. Glazer’s head for a couple of days. Instead of pointing out that his thesis may be incorrect, Dr. Glazer keeps pointing out that I mention that the data have to be normally distributed for the linear regression to work. In fact, the residuals from […]

Black Boxes and the Cochran-Mantel-Haenszel Equation

When working with statistical software programs, you should do one or two calculations by hand just to make sure the software is working properly. The last thing you want is to have an error happen because you didn’t illuminate the inside of the black box.

Odds Ratio or Marginal Effects? Depends on the Story You’re Trying to Tell.

It’s been a while since I’ve written anything, so why not entertain you with a thrilling subject? Pop quiz: If you’re presenting the results of an analysis, do you present the odds ratio or the marginal effects? Let’s say you have 150 birth records, and you want to see if smoking is associated with premature […]

The Hijacking of Fluorine 18.998, Part Three

In the last two blog posts (here and here), I told you about the history of fluoridation of water in the United States and other parts of the world. I told you how a dentist traveled out west to Colorado and, through observation and laboratory study, helped determine that adding fluoride to drinking water prevented […]

The Hijacking of Fluorine 18.998, Part Two

NOTE: This is the second of a three-part series on fluoride in drinking water and a recent study about it. You can read part 1 here. You can read part 3 here. In the last blog post, I told you all about how fluoride has been added to potable water systems in the United States […]

The Hijacking of Fluorine 18.998, Part One

NOTE: This is the first of a three-part series on fluoride in drinking water and a recent study about it. You can read part 2 here. You can read part 3 here. There is a cultural controversy dating back several decades that is very similar to the anti-vaccine controversy that we are dealing with today. […]

Sample Sizes and Statistical Significance

Some dude said I didn’t know what I was talking about because, in his world, a small sample size with a statistical significance only gets more statistically significant if the sample size increases. He’s also an antivaxxer, so…

Epi 101: Direct Age Adjustment by Hand and With R

When comparing two populations, it is essential that you know if the differences are due to different age distributions. Age can confound a lot of findings, especially if the outcome is strongly influenced by age.

One-Way ANOVA Analyses, by Hand and in R

A student asked for help with a statistical analysis the other night, and I was happy to help. However, he threw me a curveball when he told me he needed to conduct an ANOVA test using only summary data. That is, all he had was the table of results (from a publication) and not the […]