What is quartile in statistics
What is quartile in statistics 

"What is quartile in statistics" Let us discuss about what is quartile with example, why do we use quartiles, what is quartile formula, quartile definition and examples and quartile deviation.

What Is Quartile In Statistics

Quartile in statistics are the three values that divided the data into four parts, each with an equal number of observations. Quartile is a type of quantile. First quartile: Also known as Q1, or the lower quartile. Second quartile: Also known as Q2, or the median. Third quartile: Also known as Q3, or the upper quartile

In simple quartile definition and examples, the quartile is a statistical term that describes a division of observations into four defined intervals based on the values of the data and how they compare to the entire set of observations.

Quartile Example: 

If there is ungroup data to solve quartiles then 

84.60, 88.03, 94.50, 94.90, 95.05.

data is already in arranged form in ascending order.


Q1 is lower quartile 

Q1 = n+1/4 = 5+1/4 = 1.5

2nd value is quartile

which is 88.03


Q2 is the median which is 94.50. which lies in the center of the data. 

Q2 = 2(n + 1)/4 = 3 

The 3rd value in the data is Q2.


Q3 is the upper quartile

Q3 = 3(n + 1)/4 = 4.5 

4th observation is Q3

which is 94.90

Question is that, why do we use quartiles.

So the quartiles are used to calculate the interquartile range, which is a measure of variability around the median. The interquartile range is simply calculated as the difference between the first and third quartile: Q3–Q1. In effect, it is the range of the middle half of the data that shows how spread out the data is 

What Is Quartile Formula

What is quartile in statistics
What is quartile in statistics

Quartile Deviation

Quartile Deviation can be defined as the statistic that measures the dispersion. The Dispersion is the state of getting dispersed or spread. Statistical dispersion means the extent to which numerical data is likely to vary about an average value. In other words, measure of dispersion helps to understand the distribution of the data.


Quartile Deviation Definition

The Quartile Deviation can be defined mathematically, The half of the difference between the upper and lower quartile. The quartile deviation can be represented as QD; Q3 denotes the upper quartile and Q1 indicates the lower quartile.


Quartile Deviation is also known as the Semi Interquartile range.


Quartile Deviation Formula

Suppose Q1 is the lower quartile, Q2 is the median, and Q3 is the upper quartile for the given data set, then its quartile deviation can be calculated using the following formula.


QD = (Q3 – Q1)/2