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Distributions

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Source: SOURCE: TABLES AND GRAPHS BY KATHERINE WILLIAMS

This tutorial covers distributions. Distributions are essentially a description of how all of the possible values of the variable can occur. As review, let's see what a variable is. A variable is simply any characteristic of a person or a thing. Examples include age, hair color, income, weight, name, favorite type of cereal. Any of those things are describing a person or a thing that we're trying to study and that we're looking at. And they're going to vary from person to person. Not everyone is going to have the same age or hair color or favorite cereal.

So the variables are the things that are varying. And the distributions are showing us how they vary. Now when you're trying to show the distribution, you're trying to show all the possible values for that variable. You can do this in a variety of ways. You can use a frequency table, a graph, or particular mathematical rules. We'll see an example on the next slide.

Here's a frequency table. It lists all the categories, and it lists how many different pieces of data show up in that category. So it's giving us an idea of where the data is falling. We can tell pretty quickly that it's spread out between 60 and 90 feet and that there's fewer on the ends between 60 and 65, between 85 and 90, and there's a lot in the middle around this 8 and 10 chunk between 75 and 80. So that's showing us all the possible values of the variable. And it's giving us an idea of where they fall and how it's happening.

Similarly, this graph over here-- this histogram-- shows the same information. It actually shows this frequency table in a chart form. And you can tell that same kind of stuff. We can see that it runs from 60 to 90, that the highest values are in the middle, that the lower quantities are at the ends-- pieces of information like that.

Finally, we can show this information through mathematical rule, through a certain pattern. This here shows that. Another tutorial goes more in-depth into this normal distribution curve. This has been your tutorial on distributions. It's only a brief introduction, and other tutorials cover the topic in a lot more depth.