Table of Contents
The Interquartile Range (IQR) is a measure of variability in a dataset that is often used in statistical analysis. To calculate the IQR in SPSS, first select the variable of interest and click on the “Analyze” menu. Then, go to the “Descriptive Statistics” option and select “Explore”. In the dialog box that appears, move the variable of interest to the “Dependent List” and click on the “Statistics” button. From there, select “Percentiles” and make sure the box for “Quartiles” is checked. Click “Continue” and then “OK” to generate a table with the first and third quartiles, which can be used to calculate the IQR by subtracting the first quartile from the third quartile. This method allows for a quick and easy calculation of the IQR in SPSS.
Calculate Interquartile Range in SPSS
In statistics, the interquartile range represents the spread of the middle 50% of values in a dataset.
It is calculated as the difference between the 75th percentile (Q3) and the 25th percentile (Q1) of a dataset.
The easiest way to calculate the interquartile range of a dataset in SPSS is to use Analyze > Descriptive Statistics > Explore.
The following example shows how to do so in practice.
Example: How to Calculate Interquartile Range in SPSS
Suppose we have the following dataset in SPSS that shows the exam scores received by various students in some class:
Suppose that we would like to calculate the interquartile range for the exam scores.
To do so, click the Analyze tab, then click Descriptive Statistics, then click Explore:
In the new window that appears, drag Exam_Score to the Dependent List panel:
Then click the Statistics button. In the new window that appears, check the box next to Percentiles and then click the button next to Quartiles:
Then click Continue. Then click OK.
The following output will appear:
In the Percentiles table, we can see that the value at the 25th percentile is 86 and the value at the 75th percentile is 96.
Thus, here is how the interquartile range was calculated:
- IQR = 75th percentile – 25th percentile
- IQR = 96 – 86
- IQ = 10
This matches the value shown in the output.
Related:
Additional Resources
The following tutorials explain how to perform other common tasks in SPSS: