Final answer:
The scale-invariant of a data set is important when determining the similarity of an unknown sample set to a known one.
Step-by-step explanation:
The statement 'The scale-invariant of a data set is not important when determining the similarity of an unknown sample set to a known one' is False. The scale-invariant is important because it ensures that the relative distances between data points are preserved when comparing two data sets. When determining similarity, the scale (or magnitude) of the data is crucial in understanding the relationships between the data points.