Crosstabs

Correlations between different, but related, data sets are a very powerful way of starting to understand your information. In our case study, we can correlate the port of embarkation of the slaves with the main port of disembarkation. This will enable us to determine whether there was a favoured route for slaving ships across the Atlantic.

To conduct a CrossTabs function, choose Analyse | Descriptive Statistics | Crosstabs:

The Crosstabs dialogue will open. Move your chosen variables to correlate, one into the rows area, the other to columns.

Here the rows are port of disembarkation, the columns port of embarkation. Click on OK and the resultant table will be displayed on the output screen.

Two tables are presented. The first is the summary of the data, including the number of valid cases:

The second is the detailed results table:

Here we can see, for example, that the passage from the Bight of Biafra and Gulf of Guinea Islands to Jamaica was favoured by ships originating from the port of Liverpool.

Frequencies Contents Exercise 1