How Does the GMAT Adaptive Algorithm Work?
If you’re like most GMAT students, you probably beat yourself up when you miss more than a handful of quant questions. If you do a set of 31 questions and miss, say, 15 of them, you’ll probably feel like hot garbage, right?
But the GMAT scoring algorithm works in surprising ways. Because the GMAT exam is adaptive, you can afford to miss a TON of questions, and still get an excellent score. No really: you might miss as many as 50% of the questions, and still be on track for your target GMAT score.
I can miss how many GMAT quant questions?!?
Before we get too deep into the GMAT scoring algorithm, we’d like you to meet one of our all-time favorite students, a math-phobic, 34-year-old actor who we’ll call Mr. L, in honor of his appearance on the TV show Law & Order.
Before we tutored him, Mr. L took a Princeton Review GMAT course, got a horrendous score on the math section (21, which is on the wrong side of the 10th percentile), demanded his money back from Princeton Review, hired a GMAT tutor in India (where he was working at the time), and then managed to get a 33 on the GMAT quant section – a huge, huge improvement.
After that nice leap into the low 30s, Mr. L’s GMAT quant results plateaued again. He began to feel stuck, and his old insecurities about his quant skills resurfaced. He felt like he was missing far too many quant questions, and he would lose his marbles every time he missed half of the questions on a hard practice set.
Missing 50% of GMAT quant questions isn’t a disaster
After he returned to the United States, Mr. L contacted me for GMAT tutoring. After a week or two, his patience for the GMAT started to wane, and I suggested that he take a few practice GMAT quant tests – not because I thought that he was anywhere near ready to take the GMAT, but because I thought that a few practice tests would keep him a little bit more engaged than paper-based practice problems.
Mr. L pretty much crapped himself when he saw his next practice test score: he scored 40 on the quant section. I figured that it wasn't a complete fluke, since Mr. L had improved by quite a bit. But he was highly skeptical, so I asked him to take another practice test. And he hit 40 again.
Even after he repeated his perfectly decent quant performance, I struggled to convince Mr. L that he “deserved” the 40. Sure, part of the story was Mr. L’s underlying psychology: he had spent decades believing that he wasn’t a “math person”, and I understood that it would take tons of time and effort to change his self-image.
But there’s another reason why Mr. L was convinced that he didn’t “deserve” to score a 40 on the quant section: he missed nearly 50% of the questions on both practice exams.
No, you probably don’t really suck at GMAT quant.
In the American educational paradigm, getting just over half of the questions correct usually means that you barely passed the exam – and in our culture, students generally internalize a barely passing grade to mean “you suck”. Mr. L couldn't really get his head around the situation: he missed enough GMAT quant questions to feel absolutely awful about his performance, but his score was higher than he ever dreamed possible.
How many questions can you miss on a GMAT quant section?
So here's the deal: adaptive tests such as the GMAT, EA, and GRE are designed to make you miss TONS of questions – and that's one of many reasons why taking these tests can be such a painful experience.
Each GMAT question is essentially assigned a difficulty level. As an illustration, you can think of each GMAT question as, say, a "700-level" or a "520-level" question. The test basically tries to determine the level of question at which you get roughly 50-60% correct.
In other words, you can miss nearly half of the questions on the GMAT or EA quant section, and still get an excellent score. Your score is based primarily on which questions you miss, not necessarily on how many you miss.
If it helps, imagine that you're destined to earn the equivalent of a 650 on the math section of the GMAT. (Full disclosure: for the sake of simplicity, we’ll ignore some of the nuances of GMAT scoring, but this will give you a general feel for how it all works.) The first item on the quant section will be a 550-level question (roughly), and let's suppose that you answer it correctly. You'll see a harder question next, and if your skills are at a “650 level”, you probably won't struggle consistently until you see a few 650- or 700-level questions.
But it won't take too long to get to that level. If you answer the first three questions correctly, the fourth question of the GMAT quant section will probably make you sweat.
Now, imagine that the fourth question is around a 650-level question – seems reasonable enough, right? If you're a 650-level test-taker, you're likely to miss roughly half of the remaining 28 questions. This scenario is illustrated in the graph below.
Obviously, we’re making some gross oversimplifications here to make the graph look pretty, but it isn't hard to imagine that you could get a 650 on the GMAT, or perhaps something even higher... without answering more than about 17 or 18 of the 31 quant questions correctly.
How to approach the GMAT quant section
My point is this: unless your goal is a 50+ on quant, you have a huge margin for error on the GMAT. As long as you don't fall apart at the beginning of the test – or miss easier questions that you’re perfectly capable of answering correctly – you can miss tons of questions and still get a fantastic score. So if, for example, you see a crazy, indecipherable GMAT combinatorics problem, there's really not much harm in guessing and moving on. One missed question won't hurt your composite score by much, and you'll have plenty of chances to recover.
Remember that Mr. L guy, who thought that he was terrible at math? He actually deserved those 40s on the quant section, and he soon went on to complete his MBA and launch a career as a consultant and technology entrepreneur.
So as crazy as it sounds, getting 60% of the questions right might be enough to get you wherever you want to go on the GMAT math section.
Want to learn more about GMAT and EA quant?
Another story of a GMAT test-taker who was mediocre at math, but still scored a 720
How to manage your time on an adaptive test like the GMAT (6-minute video)
An article on why it’s useful to think of the section as GMAT “Quantitative Reasoning”, not GMAT “math”
Misplaced math anxiety: why you’re spending too much time on probability, combinatorics, and rates