A finite sequence of steps that reliably produces a result. An algorithm encodes a decision someone made, and hides that they made it.

That which works out a value by fixed steps. It reasons so the answer can be repeated by anyone.

The relation written so it can be reused — arithmetic with names in it, true every time its terms are.

Ordered guides to where things are. Plural of index — addresses rather than contents.

Expressed in numbers. Numeric form permits arithmetic and hides what the numbers counted.

A part expressed as hundredths of a whole. It states proportion while hiding size.

What can be said about a group that cannot be said about any member of it. Statistics describe sets, never individuals.