Shapiro-Wilk Normality Test: A Comprehensive Guide
Introduction
The Shapiro-Wilk test is a statistical test that assesses whether a given dataset conforms to a normal distribution. Understanding normality is crucial in statistical analysis, as many statistical procedures assume that data follows a normal distribution.
What is the Shapiro-Wilk Test?
The Shapiro-Wilk test is a non-parametric statistical test that evaluates the normality of a dataset. It calculates a W statistic that ranges from 0 to 1, with values closer to 1 indicating a stronger resemblance to a normal distribution.
How to Interpret the Shapiro-Wilk Test
To interpret the Shapiro-Wilk test, compare the W statistic to a critical value that corresponds to the desired significance level. If the W statistic is less than the critical value, the data is considered to deviate from normality at that significance level.
Running the Shapiro-Wilk Test in SPSS
To run the Shapiro-Wilk test in SPSS, follow these steps:
- Open the dataset in SPSS.
- Click on "Analyze" > "Nonparametric Tests" > "Legacy Dialogs" > "1-Sample K-S".
- Select the variable to test for normality.
- Click on "Options" > "Shapiro-Wilk".
- Specify the significance level.
- Click "OK" to run the test.
Conclusion
The Shapiro-Wilk test is a useful tool for assessing the normality of a dataset. By understanding the interpretation of the W statistic, researchers can determine whether their data meet the normality assumption required for many statistical procedures.
Comments