3.1 Published data sets

The Baby weight data may be useful for discussing different data types. The three variables are:

  1. Gender: The gender of the baby; one of Female or Male. This is categorical nominal.
  2. Weight: The weight of the baby in kilograms. This is numerical, continuous and ratio.
  3. Minutes: The time the baby was born, in minutes after midnight. This is numerical, continuous annd interval (since the zero is the arbitrary time of midnight.)

An online ABC article (Gibson, n.d.) reported on the impact of a $2.7 million shade structure in the Darwin CBD, reporting that it had little impact on temperatures:

The second and more recent study period, from February to July 2020, showed the average temperature under the shade structure during the peak heat hours was 31.4C, compared with 32.1C outside of it—a difference of 0.7C, or around 2 per cent.

This is an example of where temperature, an interval data type, is confused with a ratio data type. Remember that temperature has an arbitrary zero (0C is arbitrarily the freezing point of water).

Converting to Fahrenheit or Kelvin changes the percentage change, because the zero is arbitrary (Table 3.1).
Table 3.1: Percentage reduction in temperature depends on the units used
Inside temp. Outside temp. Reduction in temp. Percentage reduction
Degrees Celcius 31.40 32.10 0.70 2.2
Degrees Fahrenheit 88.52 89.78 1.26 1.4
Kelvin 304.55 305.25 0.70 0.2

References

Gibson, Jano. n.d. “FOI Documents Show Darwin’s $2.7m Shade Structure Reduces Heat by Less Than 1C.” ABC Online. https://www.abc.net.au/news/2021-02-04/darwin-shade-structure-reduces-heat-by-less-than-1-degree/13113576.