What are pivot tables, and how can they be helpful in analyzing data?
A pivot-table is a tool to dynamically show a slice and group multivariate data in tabular form.
For example, when we have the following data structure
Region Year Product Sales US 2008 Phones 125 EU 2008 Phones 352 US 2008 Mouses 52 EU 2008 Mouses 65 US 2009 Phones 140 EU 2009 Phones 320 US 2009 Mouses 60 EU 2009 Mouses 100
A pivot table can for example display a table with the sum of all products with in the rows the years and in the columns the regions.
All dimensions of the table can be switched easily. Also the data fields shown can be changed. This is called pivoting.
The tool is useful in exploratory data analyses. Because it is a dynamic tool, it can be used to visually detect patterns and outliers etc.
Most spreadsheet applications have support for this kind of tables.
An image from wikipedia: