Chapter 21 CODAP Topics

You will have learned enough to drive CODAP pretty well simply by doing the getting-started lesson.

In the next few chapters, we’ll reflect on some of the basics. Some of it is just good background to have as you get more advanced; some of it is material that is crucial for some more sophisticated techniques.

This part also includes stuff (like saving files) that you have to learn about every piece of software you use, but really has nothing to do with data science per se.

Then we’ll look at some more advanced topics that have come up when students have engaged with this material.

CODAP Terminology

Before we turn you loose, however, a few words on terminology. In a sense, what you call something doesn’t matter, especially if you are comfortable calling it something else, and you don’t create any ambiguity. We will not send the vocabulary police to your door. But we in the inside-CODAP world use specific terms to refer to things. Since we have thought pretty hard about these terms, I will share some of those with you now.

CODAP is case-centric. Everything revolves around the case. A case is a single unit of data, a row in the table, a point on a graph. If it’s Census microdata, a case represents one person. When students are confused about their data, the problem is frequently that they do not understand what the case is in their data set. And when you are designing an investigation that’s worthy of making you awash in data, “What is a case?” is often a crucial question.

Attributes are properties of the case. They appear as columns in tables. You could call them variables, but that word is already overloaded in math class. Besides, in general, they don’t vary. So we call them attributes. If a case is a person, that person might have attributes like height and political-party.

Values are the actual data that appear in the table cells. Every case has a value for each attribute. For example, suppose a case is a person with an attribute of name. That attribute might have a value of Aloysius. In a graph, that value determines where the dot goes. Some values might be missing. That’s OK; those points won’t appear in the graph. Students often confuse attributes with values; they will say, “make a graph of high school grad” when they mean, “make a graph of Education.

How that affects graphs

xxx sliders

xxx case card view