Qualitative_data_analysis

24 QUALITATIVE DATA ANALYSIS
Figure 2.5 Ordinal variable indicating order between observations
these questions raises conceptual issues which must be satisfactorily resolved if we
are use a higher level of measurement. The same applies to measurement in terms of
standard units. A standard unit is one which defines fixed limits to the intervals
between different possible values of a variable, which can be thought of as different
points on a scale. Concepts which can be measured in this way are called ‘interval’
variables. (If the scale happens to have a fixed point, such as zero, we call it a ‘ratio’
scale). For example, a ruler fixes intervals in terms of inches or centimetres, or some
proportion thereof. Fixed intervals allow us to measure the ‘distance’ between
different values, such as the difference between something 4 cms and something 10
cms wide. Once again this adds to the information about our data, this time
specifying in numerical terms the distance between different values. For example, in
Figure 2.6 our observations are measured in terms of variable ‘age at entry to
school.’
Measurement in terms of standard units is often presented as the core of scientific
method. But note that quantities mean nothing in themselves—except perhaps to
the pure mathematician. That is not to disparage the power of mathematics, which
obviously has been a crucial tool in scientific development. What tends to be
overlooked is the critical role of qualitative concepts in interpreting the
mathematics. Although we take this type of measurement for granted in the
physical world, it depends upon long-established conceptual conventions
underpinned by sophisticated theoretical relationships between categories. For
example, a metre was initially established by social convention but is now defined in