Quartiles

Example

For this example we will use data I found on Zillow this summer on house prices in West Terre Haute

60 90 70 38 101 60 250

Step 1: Find the median (Q2)

remember that we did this by first putting our data in order and then finding the center value (for odd)

38 60 60 70 90 101 250

So we see that our median (or second quartile) is 70

Step 2: Find the median of the lower half of the data (Q1)

now that we have split our data in two pieces we can find the median of the lower half

38 60 60

We see that the middle value of this lower part of our data is 60, our third quartile

Step 3: Find the median of the top half of our data (Q3)

now we look at only the top half of our data and find the median

90 101 250

We see that the middle value of the upper part of our data is 101, our third quartile 

If you want to see this done watch the following video: