Since I have written about odds ratios and logs lately, I was going to write about the natural log of the odds ratio, however, random events have caused me to do otherwise. I read an interesting blog by Adam Jackson lately, in which he is concerned that robots will take over the world. At the…
Logistic regression is based on logarithms. Ordinary Least Squares regression and analysis of variance uses the actual values as the dependent and independent variables in an equation. Logistic regression does not. What is a log, anyway? Let’s start with the very basics. First we learned to add: 5+5+5+5 = 20 After about eight years of…
I was going to write about the log of odds ratios and explain logarithms. This is the very, very odd fact I have noticed in most of social science – people in doctoral programs are often thrust into statistics course for which they really don’t have the basic mathematical foundation. This is because if they…
Going from the phi coefficient to odds-ratios. Remember the numerator for the phi coefficient was well, the odds ratio is the same two numbers DIVIDED rather than subtracted. You might think it is four numbers, but really it is not. The first number is the product of the diagonal cells (see below). The second number…
Yes, I am the F-word – a feminist. I was at a faculty meeting this weekend and one of the presenters began by saying, pointing to a colleague in the audience, “I am sure Dr. Y knows more about this than me.” Several times in her presentation on analysis of assessment data she would pause…
I hate SQL. This is probably completely irrational, like that guy I turned down for a date in junior high school who my mom always tells me founded a very successful company and is making piles of money. No wait, it wasn’t irrational, he always tried to copy off me in Algebra, plus he was…
It was 85 degrees in soCal today. Just thought I would rub that in for the benefit of my former and present colleagues in the frozen north. The advantage of having a blog as opposed to doing an on-line course is that I can just randomly switch subjects, which in my office is referred to…
We interrupt this discussion of chi-square and other categorical data analysis for a broadcast from the future … My brain is full. After three days of Macworld I have come to a number of conclusions, which I will share with you in random order, thus sparing you the expense, inconvenience and sogginess of traveling to…
People like familiarity. That’s probably one reason we enjoy the holidays so much – we know all the words to Silent Night, how to carve a turkey, which of the Christmas cookies taste the best. If I am going to convince you to give up statistics with which you feel comfortable, such as chi-square and…
Recently, someone asked me if I could explain chi-square in a few words. The short answer is, “No, I am incapable of using only a few words for any purpose whatsoever. If you doubt this, ask any of my children.” What is chi-square? Chi-square is a measure of relationship between two categorical variables. For example,…