# Why is the Standard Error Equal to Sigma Divided by the Square Root of n?

Every time I teach the Central Limit Theorem, I get questions from students on why we divide the population standard deviation, sigma, by the square root of the sample size to calculate the standard deviation of the sampling distribution which we call the standard error.

Recall that the equation for the standard error is

# “Easy” Excel Inverse Triangular Distribution for Monte Carlo Simulations Redux

Back in the dark ages when access to computers was not all that common, I was faced with developing a project schedule for, to me, a complex construction project. I was not that long out of school, so I sought out my boss with the hope he would give me some guidance on how to approach the problem.

He told me to use three-point estimation and to talk to some of the older engineers in the firm to get their ideas on the likely outcomes. So, I did and learned that the three points he was talking about were the…

# Correlation: Introduction to Relationships

In the last lesson, you learned about the Two-way Chi-square Test for Independence. Using it, you can determine if two categorical variables are independent. If two variables are not independent, they are related. Knowing something about one variable can tell you something about the other variable.

In this lesson, you will explore further this idea of variables being related, not being independent. Categorical variables that are related do not have a linear relationship for a number of reasons. One primary reason is that categorical variables are discrete, not continuous. …

# Put Christmas in the Balance

When deciding to transition

Image: Shiva Smyth/Pexels [https://www.pexels.com/photo/closeup-photography-of-stacked-stones-1051449/

Twenty-two years ago, over Easter weekend, I came out to my daughter as a transwoman. It was 1996, and she was in graduate school at Auburn University. She was a “traditional” student, meaning she had begun her college career right after high school, so she was just 21 years old. And we had always had a good relationship — father/daughter, not as close as she was with her mother, of course, but very close I felt.

So, I was optimistic that she would handle the news well. She was studying fashion merchandising…