**When do we do Pearson's Chi-square test?**

We run Pearson's Chi-square test (Crosstab) when we want to see if there is a relationship between two categorical variables.

**Example Scenario**

Final year psychology students were asked about their career plans. 12 females and 26 males said they would like to work in the field of clinical psychology, while 24 females and 8 males said they preferred the area of organisational psychology. We want to investigate if there is any relationship between gender and career preference.

In this example, our null hypothesis is that there is no relationship between gender and career preference. Our alternative hypothesis is that there is a relationship between gender and career preference.

In the data, the first column is gender and the second column is career preference. The dataset can be obtained here.

**Step 1**

Select "Analyze -> Descriptive Statistics -> Crosstab".

A new window pops out.

The two variables "Gender" and "Career Preference" will be shown on the list on the left.

**Step 2**

It does not matter which variables we select as rows and which as column. For illustration purpose, we select "Gender" as "Row(s)" and "Career_Preference" as "Column(s)".

Now click "Statistics" on the right. A new window pops out. Make sure that the "Chi-square" box at the top is checked. Click "Continue". The window will the be closed.

Click "Cells" on the right. A new window pops out. You can check the box "Observed", "Expected", "Row", "Column" and "Total" if you want to extract more information from crosstab. Click "Continue". The window will then be closed. Now click "OK" in the original window.

**Step 3**

The results now pop out in the "Output" window.

**Step 4**

We can now interpret the result.

From A in the third table, since the p-value is 0, we can reject the null hypothesis and conclude that there is a relationship between gender and career preference at 5% significant level. From the second table, it appears that males tend to work in the area of clinical psychology and females tend to work in the field of organisation psychology.

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