Basics of Data Collection


Learning Objectives

  1. Describe how a variable such as height should be recorded
  2. Choose a good response scale for a questionnaire

Most statistical analyses require that your data be in numerical rather than verbal form Therefore, data collected in verbal form must be coded so that it is represented by numbers.

Suppose you wanted to calculate the mean amount of computer experience for the five students shown in Table 1. One way would be to convert the verbal descriptions to numbers as shown in Table 2. Thus, "Very Little" would be converted to "1" and "Little" would be converted to "2."

You should think very carefully about the scales and specificity of information needed in your research before you begin collecting data. If you believe you might need additional information later but are not sure, measure it; you can always decide to not use some of the data, or “collapse” your data down to lower scales if you wish, but you cannot expand your data set to include more information after the fact. In this example, you probably would not need to record eight digits to the right of the decimal point. But recording only one decimal digit is typically too few.

Avoid forcing your subjects to do mental arithmetic. If you want to know your subjects' heights in inches, it is better to ask them to answer in feet and inches and do the calculation yourself.