A boxplot is a way to display the distribution of data that uses a five-number summary. It can tell you if there are any outliers, whether your data is symmetrical, how tightly grouped it is, and more. The five numbers are known as minimum, Q1 or first quartile, median, third quartile or Q3, and maximum.
Overview: What is Q3?
Q3 is also known as the third quartile. In the dataset, it is the middle value between the highest value and the median. It can also be called the 75th percentile.
3 benefits of Q3
There are a few benefits to the third quartile:
1. Informs
The first and third quartiles give us valuable information about our data’s internal structure.
2. Helps to find the interquartile range
You need Q3 in order to find the interquartile range, which is the difference between Q3 and Q1.
3. It is a solid ranking
In testing, if you score within Q3, you have scored better than 50% of your peers.
Why is Q3 important to understand?
Understanding Q3 is important for a host of reasons:
To fully understand a boxplot, you need to know all five values.
In a boxplot, all five values play important roles and show key information. Thereby, it is important to understand all of them.
Dividing the data
It is important to understand the third quartile so that you know how to properly divide and subdivide the data set in order to make a boxplot.
Interquartile Range
It is important to understand Q3 in order to find the IQR or Interquartile Range. This is the range where you find 50% of the data points and it is the difference between Q3 and Q1.
An industry example of Q3
A machinist at a manufacturing plant is studying for a promotion. If they get the promotion, the machinist will be placed on a new state-of-the-art machine and receive higher pay. In order to advance, they need to score within the third quartile or greater on a safety test for the new machine.
3 best practices when thinking about Q3
Here are some things to keep in mind when it comes to the third quartile:
1. Find the median
In order to find the first and third quartiles, it is important to find the median of the data set.
2. Remember how many elements of a data set are between the first and third quartile
There will be one-half of the data sets in between these quartiles.
3. Remember the percentage of elements that the third quartile holds above the median
It is 25%
Frequently Asked Questions (FAQ) about Q3
What is the f value of Q3?
The f value of Q3 is 0.75.
What percentage of value is greater than Q3?
The percentage of values in a data set that is greater than Q3 is 25%.
How many quartiles are there in a data set?
There are three quartiles in a set of data.
Q3 and its usage
If you are going to be working with boxplots as a way of displaying data, you will need to know Q3 and its function as well as the other numbers in a five-number summary.
