BALA201 LECTURE NOTES
Topic 3
Descriptive statistics
Descriptive statistics refers to methods of describing and summarising data using
tabular, visual and quantitative techniques.
Metrics and data classifications:
Metric - "a unit of measurement that provides a way to objectively quantify
performance".
Measurement - the act of obtaining data associated with a metric.
Measures - numerical values associated with a metric.
Metrics can be DISCRETE or CONTINOUS
-
Discrete: from counting something e.g., number of errors
-
Continuous: on a continuous scale e.g., length, weight
Data classifications (measurement scales)
categorical (
nominal
) data - sorted into categories according to specified characteristics.
ordinal data
- can be ordered or ranked.
interval data
- ordered, with constant differences between observations and many have
arbitrary zero points.
ratio data
- continuous and have a natural zero.
Scaling e.g.
Nominal - numbers assigned to runners.
Ordinal - rank order of winners
Interval - performance rating on a 0-10 scale
Ratio - time to finish in seconds.
