The interquartile range is the difference between the Lower quartile and the upper quartile. Obviously you need to be able to find these values. Haylock (2006) explains how to do this for difficult size groups in mathematics explained for primary teachers. He explains the position of the lower quartile is a quarter of (n+1) and that of the upper quartile is three-quarters of (n+1). So for a group of 7 numbers, you find a quarter of 8, which is 2. Therefore the number in second place is the lower quartile. Three quarters of 8 is 6 and so the number in 6th position is the upper quartile. Now take the lower quartile from the upper quartile.
A quartile divides a grouping into four. The first quartile will have the first 25% of the group, the second quartile will have the second 25% of the group, the third quartile will have the third 25% of the group and the last quartile will have the last 25% of the group. For example if a classroom had 20 students who had all taken a test, you could line them up, the top 5 marks would be in the first quartile, the next five would be in the second quartile, the next 5 would be in the third quartile, and the 5 students with the lowest marks would be in the last quartile. Similarly, a percentile divides a grouping, except the group is divided into 100. Each 1% represent 1 percentile.
Find the difference between the values for quartile 3 and quartile 1.
First Quartile = 43 Third Qaurtile = 61
The sides of the box are the quartile values: the left is the first quartile and the right is the third quartile. The width, therefore is the interquartile range.
The lower quartile is the second smallest and the upper quartile is the fourth smallest (second largest).
The second quartile.
50%. The second quartile is the median.
Subtract the lower quartile from the upper quartile.
The median
The interquartile range is the difference between the Lower quartile and the upper quartile. Obviously you need to be able to find these values. Haylock (2006) explains how to do this for difficult size groups in mathematics explained for primary teachers. He explains the position of the lower quartile is a quarter of (n+1) and that of the upper quartile is three-quarters of (n+1). So for a group of 7 numbers, you find a quarter of 8, which is 2. Therefore the number in second place is the lower quartile. Three quarters of 8 is 6 and so the number in 6th position is the upper quartile. Now take the lower quartile from the upper quartile.
Another name for second quartile, Q2, is median. It is also sometimes referred to as P50.
A quartile divides a grouping into four. The first quartile will have the first 25% of the group, the second quartile will have the second 25% of the group, the third quartile will have the third 25% of the group and the last quartile will have the last 25% of the group. For example if a classroom had 20 students who had all taken a test, you could line them up, the top 5 marks would be in the first quartile, the next five would be in the second quartile, the next 5 would be in the third quartile, and the 5 students with the lowest marks would be in the last quartile. Similarly, a percentile divides a grouping, except the group is divided into 100. Each 1% represent 1 percentile.
Step 1: Find the upper quartile, Q3.Step 2: Find the lower quartile: Q1.Step 3: Calculate IQR = Q3 - Q1.Step 1: Find the upper quartile, Q3.Step 2: Find the lower quartile: Q1.Step 3: Calculate IQR = Q3 - Q1.Step 1: Find the upper quartile, Q3.Step 2: Find the lower quartile: Q1.Step 3: Calculate IQR = Q3 - Q1.Step 1: Find the upper quartile, Q3.Step 2: Find the lower quartile: Q1.Step 3: Calculate IQR = Q3 - Q1.
Iqr stands for inter quartile range and it is used to find the middle of the quartiles in a set of data. To find this, you find the lower quartile range and the upper quartile range, and divide them both together.
Find the difference between the values for quartile 3 and quartile 1.
Find the difference between the values for quartile 3 and quartile 1.