# Conducting One-Way ANOVA in SPSS

Nikki Kamouneh

Posted on
anova SPSS

We want to study the effectiveness of different treatments on anxiety. We collect a sample of 75 subjects in the following categories:

• No treatment ($$n_1$$ = 27).
• Biofeedback ($$n_2$$ = 24).
• Cognitive-behavioral Treatment ($$n_3$$ = 24).

The dependent variable is anxiety levels. In this analysis, we will include both planned contrasts and post hoc comparisons.

## Steps to doing an ANOVA

The steps to doing an ANOVA in SPSS are as follows:

### 1. Assert the null hypothesis: all means are equal.

• $$H_0$$ : $$\mu_1 = \mu_2 = \mu_3$$
• $$H_A$$ : At least two $$\mu_i$$’s are different

If even two of the means are significantly different, we reject the null hypothesis.

### 2. Visualize the data.

We can visualize the data by box plots to check for normality and equality of variances across groups.

We will do this in SPSS by going to Graphs>Legacy Dialogues>Boxplots.