Basics of Data Collection
Prerequisites
None
Learning Objectives
 Describe how a variable such as height should be recorded
 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.
