One of the most common challenges in a data-driven story is combining two sets of data — such as events and populations — to put a story into context. In an extract from the ebook Finding Stories in Spreadsheets, I explain how to use lookup functions to combine two tables. The longer ebook version of this tutorial includes a dataset and exercise to employ these techniques.

Combining data is often a great way of telling new stories about spreadsheets. For example: you may have one table showing pass rates for each school in an area, and another table showing their addresses. Combining these would allow you to identify geographical patterns, or to place them on a map.

You could also combine the addresses with poverty rates for different locations, or unemployment to see if there’s a possible relationship (remembering that correlation does not equal causation), or to identify the schools performing particularly well despite local conditions. In the video below, for example, I walk through an example of combining data on different sports teams’ attendances with data on their rankings, allowing you to see who’s attracting large crowds despite their poor performance.

The VLOOKUP function is one of the most widely-used tools in combining data in this way. It stands for Vertical lookup, and means that the spreadsheet will look up and down a column (i.e. vertically) for whatever you ask it. In more recent versions of Excel the XLOOKUP function has been introduced to make the process easier — but the process is similar for both.

Continue reading →