Fact: within the course of each Quantitative section, you will have, on average, two sets of Data Interpretation questions. Each set will present data in some form (graph, table, etc.), and you will have two or three consecutive questions on that same data set.
Why does the GRE ask Data Interpretation questions?
Absolutely in the natural sciences, and to a great extent in the social sciences as well, data is king. All scientific authority rests on, or falters in the face of, good scientific data. If you are planning graduate studies in the natural or social sciences, I imagine it’s neither a surprise nor a challenge that the GRE would ask this.
What about the poor crunchy artsy non-techy humanities majors? Yes, it is unfortunate that the general GRE is a one-test-fits-all kind of thing. I would say, though, whether you do science or not, and whatever opinions you may have about science and technology, we all live in a world in which we have been ineluctably affected by science and technology. To that extent, important parameters of our lives have been and will continue to be shaped by the data discovered by scientists. Any intelligent person should have at least basic competency in interpreting the data that can impact our lives. That’s why the GRE asks about it.
What are the formats of GRE Data Interpretation questions?
Much of this question type is about your ability to read graphs & charts showing data, and really what the GRE is asking is for the most part quite straightforward. The vast majority of these questions revolve around one of the “big five” types of data display:
- Pie Chart
- Column Chart
- Line Chart
- Bar Chart
- Numerical Table
Sometimes, the Data Interpretation set might combine two types — for example, a Pie Chart showing the general breakdown of governmental expenses, and then another chart or table of numbers showing the detail in one category. In rare circumstances, the Data Interpretation might be an entirely different kind of visual information, say, the floorplan of a house, but in those cases, the questions are often particularly simple.
“Bar Charts” vs. “Column Charts”
ETS calls a chart a “bar chart” whether the bars are horizontal or vertical. Nevertheless, many sources (such as MGRE) call charts withe horizontal bars “bar charts” and charts with the vertical bars “column charts.” Regardless of the names we use, there is a subtle difference. In general, if the bars represent selected members of a particular category, with no attempt to exhaust the whole categories, and with no particular order among the members, they are represented as horizontal bars, what many folks would call a “bar chart.” For example, if the categories are seven different fruits, seven different makes of car, or seven different nations, those do not nearly exhaust those respective categories, and given the set of seven, there’s no inherent way to order them. (They probably would be listed simply in alphabetical order, for lack of a more meaningful ordering system.) Thus, they would be represented by horizontal bars.
If the categories either have an intrinsic order to them (e.g. various years) or if they represent the full complement of a category (e.g. the three divisions of a corporation), then they would tend to be represented with vertical bars, what many folks would call a “column chart.” Sometimes, column charts are segmented (each bar broken into categories, and sometimes, they are equal height columns where the segments represent percents.
Either variety can have side-by-side bars, if you are displaying two different measurements about each category.
How do I begin studying for GRE Data Interpretation?
Start looking for data displayed in graphs & charts. Any day’s issue of, say, the New York Times is likely to have at least one chart or graph accompanying an article somewhere. That’s even more true for any week’s issue of the Economist, arguably the single most intelligent weekly magazine in print. Why does a chart or graph accompany that article? What information is given in the chart that is not given in the article? What aspects of the data does the chart make clear? If you simply can understand what a graph or chart adds to a written article, you are more than well on your way toward mastering GRE Data Interpretation.
Be sure to check out Chris’ post on strategies for Data Interpretation. Below is a sample Data Interpretation for further practice. And, of course, sign up for Magoosh, where we will help you perform better on Data Interpretation and all other types of questions on the GRE.