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Explanatory and Response Variables

Explanatory and Response Variables

Author: Katherine Williams

Identify the explanatory and response variables in a scatterplot.

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This tutorial covers explanatory and response variables. As a review, a variable is a characteristic of a person or a thing. And then sometimes when you have the set of variables, it's going to make sense to pick an explanatory variable and a response variable.

That's not always going to be true. Sometimes it's not going to have a clear explanatory and response variable, and that's OK.

But what an explanatory variable is, it's one that might cause an effect. So the explanatory variable is the thing that you're looking to cause something to happen. And the response variable, on the other hand, is the one that's going to reflect that effect.

And the explanatory variables, when you're making a scatter plot, are going to go in the x-axis. And the response variables are going to go in the y-axis.

Now, if you don't have a clear-cut explanatory and response variable, then it doesn't really matter which one goes on the x and y. You can choose either. You can try graphing it with both on there and choose which one gives the right picture that you're looking for. But when you have explanatory and response, then it has to go x for explanatory, y for response.

So in this first example here, it says we're comparing two variables. The first variable is the age of a young farm animal and the second variable is the weight of a young farm animal. Here, it's going to make sense that there's an explanatory and a response.

We think that age would have an effect on the weight. So the age is going to be the explanatory variable. And so then we're going to put that on the x. Whereas, the weight is going to be the response variable, so that would go on the y.

Now with example 2, it says a student's grade in English and a student's grade math. There, it's not as clear cut. We don't know whether the English grade is causing you to have a better math grade or the math grade is causing you to have a better English grade, or there's something else outside. So you can pick either x or y for the English grade, and then the math grade just goes in the other axis.

So here we're just looking at the example 1 that we just had. And we said that the age was the explanatory variable, and we want that to go on the x-axis. So this one here is the x-axis. And then the weight, we think is the response, so we think it's the y.

And one trick I use to keep the x-axis and the y-axis separate, because I forget sometimes, is the y-axis you can turn it into a capital Y. So it has the little top part that you can add onto it. So that can help you to remember the y is the one that's vertical.

Now this has been your tutorial on explanatory and response variables. The key thing to remember here is that with a scatter plot, the explanatory goes in the x-axis and the response goes on the y-axis.

Terms to Know
Explanatory Variable

The variable whose increase or decrease we believe helps explain a tendency to increase or decrease in some other variable.

Response Variable

The variable that tends to increase or decrease due to an increase or decrease in the explanatory variable.