Category: GRE Data Analysis

Do you know the difference between permutation and combination? No? You’re not alone. When it comes to GRE data analysis, combinations and permutations are the bane of many students. Yet, what I’ve noticed over the years is it’s not so much both of them that are the issue as it is which one to use […]

When trying to decide whether to use the combination formula, many students have trouble applying the “does order matter” test–deciding if outcomes differ. It’s easy to say order doesn’t matter when it in fact does, and vice versa. Once you get it, it’s really useful, but it can take a bit of thinking and re-thinking. […]

Back in the days of the old GRE, there was only one book out on the market written by ETS (the creators of the test): the hoary 1991 tome Practicing to Take the GRE. At that point, there were few, if any questions, relating to statistics (probably a straightforward median and mode question). Of course […]

There are few concepts on the GRE that frighten students more than that of probability. Many go out of their way to study difficult probability questions, agonizing over concepts that are beyond the scope of the GRE. Test day, though, you might only see one probability question. You will probably see two, though you might […]

First, a practice question about the following scenario. In a survey, 86 high school students were randomly selected and asked how many hours of television they had watched in the previous week.  The histogram below displays their answers.     1)   Histogram First, a reminder on histograms.  Histograms are not simple bar or column […]

One category of graph you certainly could see on GRE Data Interpretation questions is the scatterplot, and its associated idea of the best fit line. Let’s talk about how these beasts operate! Scatterplots To begin, let’s review scatterplots.  When each data point (each person, each car, each company, etc.) gives you a value for two […]

Fact: An 8 year old boy who is 4’5″ (53 inches) tall is in the 86th percentile for height for his age. What on earth does that mean?  Well, the percentile of an individual tells you what percent of the population has a value of a variable is below that individual’s value of the variable.  […]

Many quake in their boots when they hear that there will be Statistics covered on the GRE. They run to their college stats textbooks, dust off the cover, roll up their sleeves, and start computing the standard deviations of a list of twenty, three-digit numbers. Stop, if this in anyway describes you. The Statistics on […]

Statisticians point out that it’s often useful to “chunk” data to understand it.  What does it mean to “chunk” data? It means dividing a long list into smaller chunks so that, with a few well-chosen numbers, we can get a sense of the layout of the list. The fundamental “chunking” number is the median.  The […]

A distribution is a graph that shows what values of variable are more or less common in a population. Where the graph is higher, there are more people, and where the graph has a height close to zero, there are fewer people.   By far, the most famous and most useful distribution is the Normal […]