The lower quartile, or first quartile (Q1), is the value under which 25% of data points are found when they are arranged in increasing order. The upper quartile, or third quartile (Q3), is the value under which 75% of data points are found when arranged in increasing order.
How do I find the lower quartile?
To find the lower quartile of a set of data, we can find the median of the data and then find the median of the first half. This strategy is similar to dividing a cake into halves, and then dividing one of the halves in half so that you end up with a quarter of the cake.
How do you find the upper and lower quartiles?
Quartiles and interquartile range
- the lower quartile is the median of the lower half of the data. The. ( n + 1 ) 4 value.
- the upper quartile is the median of the upper half of the data. The. 3 ( n + 1 ) 4 value.
