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To calculate percentiles using SPSS, you can use the “Percentile” function under the “Analyze” tab. First, select the variable you want to calculate the percentile for. Then, specify the desired percentile value (e.g. 25th, 50th, 75th) and click “Continue.” SPSS will then generate a new variable with the percentile values for each observation. You can also use the “Rank Cases” function to rank the data and then use the “Case Summaries” function to calculate the percentile values for each variable.
The nth percentile of a dataset is the value that cuts off the first n percent of the data values when all of the values are sorted from least to greatest.
For example, the 90th percentile of a dataset is the value that cuts of the bottom 90% of the data values from the top 10% of data values.
The easiest way to calculate percentiles for a variable in SPSS is to use Analyze > Descriptive Statistics > Percentiles.
The following example shows how to calculate percentiles in practice.
Example: How to Calculate Percentiles in SPSS
Suppose we have the following dataset that contains information about points scored by basketball players on various teams:
Suppose that we would like to calculate percentiles for the Points variable.
To do so, click the Analyze tab, then click Descriptive Statistics, then click Percentiles:
In the new window that appears, drag the Points variable into the Variables panel.
By default, SPSS will calculate the 5th, 10th, 25th, 50th, 75th, 90th, and 95th percentiles.
Once we click OK, we can see each of these percentiles for the Points variable:
For example, we can see:
- The value at the 5th percentile is 8.8.
- The value at the 10th percentile is 12.4.
- The value at the 25th percentile is 14.
Note: Tukey’s Hinges are simply the values at the 25th, 50th and 75th percentiles. These represent the first, second and third quartiles of the dataset, which are the values that divide the dataset into four pieces.
If you’d like, you could also specify the exact percentiles to calculate by clicking the button next to Custom and then manually typing the percentile values and clicking Add after each value.
For example, we could enter the percentiles ranging from 10 to 90 by intervals of 10:
Once we click OK, these percentile values will automatically be calculated for the Points variable:
For example, we can see:
- The value at the 10th percentile is 12.4.
- The value at the 20th percentile is 13.8.
- The value at the 30th percentile is 14.4.
And so on.
Additional Resources
The following tutorials explain how to perform other common operations in SPSS: