From the course: SQL for Exploratory Data Analysis Essential Training
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Calculating quartiles - PostgreSQL Tutorial
From the course: SQL for Exploratory Data Analysis Essential Training
Calculating quartiles
- [Instructor] Another way of thinking about the distribution of data is to calculate quartiles. Quartiles are dividing points between sections of ordered data. One of the data points we use is the median. Let's take a look at the first half of the ordered set of data. Let's find the median for that. That gives us another dividing point. Similarly, now let's take a look at the second half of the data points, and let's find the median in that second half. That gives us a third data point. As you can see, the dividing points break up the ordered list of values into four equal parts. These are quartiles, and they're numbered from one to four. Let's look at an example of a sorted list of 17 numbers. The median or midpoint number is seven. Now let's take a look at the first half of the series. The series has eight numbers, so the median is the average of the fourth and fifth numbers in the list. In this case, the…
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