IN THIS CHAPTER
Working with ranks in files
Rolling in the percentiles
In my left hand, I hold 100 Philippine pesos. In my right, I hold 1,000 Colombian pesos. Which is worth more? Both are called pesos, right? So shouldn’t the 1,000 be greater than the 100? Not necessarily. Peso is just a coincidence of names. Each one comes out of a different country, and each country has its own economy.
To compare the two amounts of money, you have to convert each currency into a standard unit. The most intuitive standard for U.S. citizens is our own currency. How much is each amount worth in dollars and cents? As I write this, 100 Philippine pesos are worth over $2. One thousand Colombian pesos are worth 34 cents.
So when you compare numbers, context is important. To make valid comparisons across contexts, you often have to convert numbers into standard units. In this chapter, I show you how to use statistics to do just that. Standard units show you where a score stands in relation to other scores within a group. ...