Data Interpretation: Read the Chart Before You Touch the Numbers
Here is a scene I watch every single week. A GRE Test Taker hits a chart question, glances at the bars, grabs two numbers, punches them into the on-screen calculator and picks an answer in 40 seconds. Feels great. Feels FAST. Then comes the review: wrong. And the first thing out of their mouth is "I must have messed up the math."
No. The math was fine. The calculator does not make arithmetic mistakes. What went wrong happened BEFORE a single number got touched. They read the chart wrong.
What these questions are really testing
The GRE has two Quant sections (Quantitative Reasoning, the math part of the test), each with 20 questions in 35 minutes. Inside those sections, some questions come as a group that all share one table, bar graph, line graph or pie chart. These are called Data Interpretation questions, and you can see how ETS describes them on its Quantitative Reasoning page.
Here is what most people miss. The math in these questions is usually basic: percents, ratios, a little averaging. The hard part is the READING. The question writers know that a rushed Test Taker reads the bars and skips the words. So they hide the trap in the words: the title, the units, the key that tells you which color is which, the little note under the chart.
Stop reading for a second and think about the last chart question you missed. Was it really the arithmetic? I'll bet it wasn't. I'll bet you used a number from the wrong year, or the wrong group, or you used a percent when you needed a dollar amount. Be honest with yourself here, because you cannot fix a problem you refuse to name.
Read the chart like a contract
When a chart shows up, do NOT look at the question yet. Spend a short moment on the chart itself and write a few notes on your scratch paper:
- What is being measured? Read the title word for word. "Revenue" and "percent of total revenue" are two totally different things.
- What are the units? Dollars, thousands of dollars, people, percents?
- What does each column, color or line stand for? Which one is 2014 and which is 2015?
- Is there a total or a note anywhere? A tiny line under the chart can change every answer in the set.
That is maybe four short lines of notes. Now try one.
The mistakes I see, and what to do INSTEAD
Treating a percent like an amount. If the chart shows shares of a total, the shares alone cannot tell you whether the actual amount went up or down.
INSTEAD: Every time you see a percent on a chart, ask "percent of WHAT?" and write the answer down.
Skipping the units line. A chart labeled "in thousands" turns 45 into 45,000. Miss that and you will pick an answer that is off by a factor of 1,000, and yes, that answer will be on the list.
INSTEAD: Put the units in your notes next to the title, every time, even when it feels obvious.
Reading the question before the chart. You go hunting for one number, find something that looks right, and grab it without knowing what the chart actually measures.
INSTEAD: Chart first, question second. The few seconds you spend pay off on every question in the group.
Doing the comparison in your head. "North went down, South went up, I got it." That is exactly how the trap in the example works. I wrote a whole post on why working in your head is pride, not speed, and chart questions are where that pride costs the most.
INSTEAD: Write the two numbers you are comparing on paper, with their labels, before you compare anything.
Calculating to the penny when the answers are far apart. If the choices are 4%, 17% and 25%, you do not need three decimal places.
INSTEAD: Look at the answer choices before you calculate. If they are spread out, estimate and move on.
Re-reading the whole chart for every question in the group. Each re-read burns time you could be spending on the actual work.
INSTEAD: Take your chart notes ONCE, at the start, and work from your notes for the rest of the group.
Now use the same table again. This one is a "select one or more" question, which means more than one choice can be correct and you have to pick every choice that works.
Why this matters more than you think
Chart questions come in groups. One misread title does not cost you one question. It can cost you EVERY question built on that chart. Fix the reading and you are not picking up one point, you are picking up a cluster of them.
And notice what you did NOT need in either example: advanced math. You needed percents, one subtraction and one division. The GRE is a predictable, standardized test. The traps repeat, so you can train for them. The score you get is the score you earn, and on chart questions the points are earned with your eyes and your pencil before the calculator ever comes out.
Your assignment for today
Pull up every chart question you have missed in practice, whether from your books or ETS's free POWERPREP practice tests. For each one, write down the EXACT word or label on the chart that you misread. Not "I messed up." The word. If you cannot name it, redo the question from scratch, taking your chart notes first, and find it. You are not allowed to have "no idea." Then do three fresh chart questions with notes on paper before you look at a single question. Do it today, not after your next practice test.
