How to check for outliers in multiple regression spss

Summary

Outliers are basically values that fall outside of a normal range for some variable. But what's a “normal range”? This is subjective and may depend on substantive knowledge and prior research.

Alternatively, there's some rules of thumb as well. These are less subjective but don't always result in better decisions as we're about to see.

In any case: we usually want to exclude outliers from data analysis.

So how to do so in SPSS?

Outliers spss z-score

We'll walk you through 3 methods, using life-choices.sav, partly shown below.

In this tutorial, we'll find outliers for these reaction time variables.

During this tutorial, we'll focus exclusively on reac01 to reac05, the reaction times in milliseconds for 5 choice trials offered to the respondents.

Method I - Histograms

Let's first try to identify outliers by running some quick histograms over our 5 reaction time variables.

Doing so from SPSS’ menu is discussed in Creating Histograms in SPSS. A faster option, though, is running the syntax below.

*Create frequency

how to deal with outliers in regression spss

how to do outlier analysis in spss