Cases

Without cases, there are no data. Sometimes you will encounter cases referred to as records, or even rows (in a spreadsheet). The range of possibilities for what a case represents is vast: a planet, a car, an element, an experiment, a set of measurements, a child, a race, a baseball player, a roll of five dice, a poker hand, a country, a crime, the weather at a particular place and time, a purchase, a song, a family, a building.

It is essential to understand the difference between situations in which you have information about each case and situations in which you only have summary information. Often these two kinds of data are referred to as raw data and summary data. Fathom works well with raw data because it allows you to explore that data and to look for relationships. Fathom does not work well if all you have is summary data because the interesting work of deciding what to look at has already been done by the person who created the summary.

The distinction between raw data (or microdata) and summary data is not necessarily clear cut. The table shows summary data for each state: its population and the number of prisoners. You could think of each person in the country as a case and realize that you don’t have the raw data. But you could also consider each state as a case, and realize that you can do an interesting analysis of the relationship between a state’s population and the number of prisoners it has.

_img51