How does a box and whisker plot work how to#

Here’s how to do it: First, make sure your list of whisker numbers is arranged in order from smallest to largest:Īnd that’s it! You’ve created a box and whisker plot that clearly shows the median (the line at the center of the box), the full range (the extent of the whiskers), and a measure of the typical width of the distribution (the box contains half of all the data points). And the best part is that it’s pretty easy to make. In one glance, the box and whisker plot tells you how the numbers in a distribution are arranged, and where the majority of them are located. That’s precisely what a box and whisker plot does. But wouldn’t it be nice if we could come up with a way to visualize what this distribution of cat whiskers looks like? How to Make Box and Whisker Plots So, the mean and median are both 24, and the range is 8. What does your statistical sample of whisker numbers look like? Well, let’s imagine you find cats with 20, 21, 22, 23, 24, 25, 26, 27, and 28 whiskers.

Now, imagine going out into the world and staring into and below the eyes of 9 cats in order to count their whiskers. Some cats have fewer (occasionally they fall out and are replaced), and, for the sake of our argument here, let’s assume that some cats have more. And, after a bit of research, I’ve discovered that cats typically have a total of 24 whiskers-12 on each side of their nose, all arranged in four horizontal rows. What Is a Box and Whisker Plot?Īnd that brings us to the most important question of the day: How many whiskers does a cat have? That’s right-since we’re talking about box and whisker plots, I thought it appropriate to have a feline-focused question. That’s all we’ll say for now-we’ll talk more about the standard deviation next week. But what’s important about the standard deviation? Well, the take-away message is that whereas the range tells us about the overall spread of numbers in a group, the standard deviation tells us how far the numbers are spread away from the group’s mean. If you want to see an explanation of how to calculate the true standard deviation, check out last week’s Math Dude “Video Extra!” episode. In the last article, we also talked about an approximation to the standard deviation (which I called the quasi-standard deviation) that’s a bit easier to understand and calculate than the real thing. Clearly, these two groups are different despite having the same mean. In contrast, sophomores are generally 15 and 16 year old, so the range of the ages of sophomores is 16 – 15 = 1. So, since freshmen typically enter high school when they are 14, and seniors graduate when they are 18 (hopefully!), the overall range of the ages of high schoolers is 18 – 14 = 4. The range is simply the overall spread in a group of numbers. Clearly it’s important to distinguish whether or not two groups with similar average properties are, in fact, similar-and that’s where the concepts of range and standard deviation that we talked about last time shine.

How does a box and whisker plot work