1.1 Types of data

  • Most data can be put into two categories:
  1. Qualitative data are the result of describing attributes of an observations. They are often called categorical data and generally labeled by words or letters, e.g. hair color, type of car, etc.
  • Researchers and practitioners prefer to use quantitative data over qualitative (categorical) data because it lends itself more easily to mathematical calculations
  1. Quantitative data are always numbers, like amount of money, weight, number of students who take business statistics course, etc.
Data that are the result of counting are called quantitative discrete data, e.g. if you
count the number of phone calls you receive for each day, you might get values
such as 0, 1, 2, 3, 4 or 5.
Data that are not only made up of counting numbers, but that may include
fractions, decimals, or irrational numbers, are called quantitative continuous
data, e.g. length of the phone call might get values such as 7.5 minutes, 1.3 minutes,...

Example 1.1 The data are the number of books that students carry in their backpacks. You sample five students. Two students carry three books, one student carries four books, one student carries two books, and one student carries one book. Indicate the type of data.

Example 1.2 The data are the weights of backpacks with books in them. You sample the same five students. The weights (in pounds) of their backpacks are \(6.2\), \(7.5\), \(6.8\), \(9.1\) and \(4.3\). Indicate the type of data.

Example 1.3 Determine the correct data type (quantitative or qualitative). Indicate whether quantitative data are continuous or discrete.

  1. the number of pairs of shoes you own
  2. the type of car you drive
  3. the distance from your home to the nearest grocery store
  4. the number of classes you take per school year
  5. the type of calculator you use
  6. the number of correct answers on a quiz