What Are Data?

Statistics is the science of collecting, organizing, analyzing, and interpreting data in order to make decisions.

Data consist of information coming from observations, counts, measurements, or responses. (Single value = datum, while data is the collect of values)

In other words, data is the information that you collect and statistics is what you do with that information.

But data values, no matter what kind, are useless without their context. In order to provide context to your data you should establish "The 5 W's": Who, What, When, Where, and Why. Sometimes How is added to the list as well. Most importantly, if you can't answer the Who and What then you don't have data and you don't have any useful information.

Who?

The following vocabulary pertains to answering the question "Who" for your data.

Case - A case is an individual about whom or which we have data.

Respondent - A respondent is an individual who answers a survey.

Subject - People on whom we experiment are subjects. More specifically, people in an experiment are called participants, but animals, plants, Web sites, and other inanimate subjects are often called experimental units.

Often, the cases are a sample selected from some larger population that we'd like to understand.

Where, When and How?

The more we know about the data, the more we'll understand about the world. If possible, we'd like to know the When and Where of data as well. Values recorded hundreds of years ago may mean something different than similar values recorded today. Likewise, values measured in a different countries may differ in meaning as well. How the data are collected is probably one of the most important as it can make the difference between insight and nonsense. One primary concern of Statistics is designing methods for collecting meaningful data.

Throughout this course, we'll often provide a note listing the W's (and H) of the data. It's a recommended habit. The first step of any data analysis is to know why you are examining the data, whom each row of your data refers, and what the variables record.

How do we collect Data?