Where Are the Data?

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Fathom Overview > Where Are the Data?

Data are stored in a collection. A collection contains cases. Cases have attributes. Attributes have values, usually different values for each case. Attributes can also have units or category sets.

By way of example, suppose you have conducted a survey. The results of your survey are stored in a collection. Each case in the collection represents one person who filled out the survey. The cases have attributes corresponding to the questions on the survey: sex, height, age, favorite color, and so forth. The values of these attributes vary from case to case; one person is “male” and the next “female,” one person’s height is 165 cm, and another’s is 170 cm, and so on. The attribute height has the unit centimeters; and the attribute sex has a category set {male, female} that defines its valid values.

A closed (iconified) collection appears as a box of gold balls.

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An open collection displays each case as a gold ball. (You can change the placement and appearance of the cases. See Change the Appearance of Cases in a Collection.)

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In a case table, each row represents one case, and each column represents one attribute.

In a dot plot, each dot represents one case, and attributes appear on axes.

To decide how to structure your data, ask “What does a case represent?” For example, if you are recording people’s height and sex, you’ll want to make each case a person with two attributes: height and sex. Although you could record male heights in one attribute and female heights in another attribute, a case would then consist of a pair of heights; however, this pairing would be arbitrary and would get in the way as you analyze the data.

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See Work with Collections.