Choosing which variable to place on the x-axis and y-axis in a graph is an important step in data visualization

Choosing which variable to place on the x-axis and y-axis in a graph is an important step in data visualization. Here are some guidelines to help you decide:

1. Independent vs Dependent Variables: The independent variable (or “explanatory variable”) should go on the x-axis and the dependent variable (or “response variable”) should go on the y-axis1. In other words, the variable that can be viewed as “explanatory” should go on the x-axis and the variable that is “being explained” should go on the y-axis1.

2. Experimental Control: If one variable was under experimental control, it should be placed on the x-axis2.

3. Prediction: If you would like to make predictions of one variable based on the other, put the one you’re predicting on the y-axis and what you’re basing it on on the x-axis2.

4. Random vs Fixed Variables: In some cases, if one variable is ‘fixed’ and the other is ‘random’, the random one tends to go on the y-axis of the plot2.

Here are a few examples:

• Hours Studied vs. Exam Score: If a professor collects data on the number of hours studied and exam score received, he should place ‘Number of hours studied’ on the x-axis and ‘Exam Score received’ on the y-axis. Since the exam score received is dependent on the number of hours studied, the number of hours studied belongs on the x-axis while the exam score belongs on the y-axis1.

• Food Consumption vs. Weight: If a biologist collects data on grams of food fed daily and weight after one month for mice in his lab, he should place ‘Grams of food fed daily’ on the x-axis and ‘Weight after one month’ on the y-axis. Since the weight of each mouse is dependent on the number of grams of food they’re fed daily, the number of grams of food belongs on the x-axis while the weight belongs on the y-axis1.

• Age vs. Height: If a botanist collects data on height (in inches) and age (in weeks) for a certain plant, she should place ‘Age (in weeks)’ on the x-axis and ‘Height (in inches)’ on the y-axis. Since the height of the plant is dependent on its age, age belongs on the x-axis while height belongs on the y-axis1.

Remember, regardless of what you do, always label axes clearly2. I hope this helps! If you have any more questions, feel free to ask.