The Art of Statistics: Learning from Data

by David Spiegelhalter

Data has two main limitations as a source of such knowledge. First, it is almost always an imperfect measure of what we are really interested in: asking how happy people were last week on a scale from zero to ten hardly encapsulates the emotional wellbeing of the nation. Second, anything we choose to measure will differ from place to place, from person to person, from time to time, and the problem is to extract meaningful insights from all this apparently random variability

The crucial distinction is that deduction is logically certain, whereas induction is generally uncertain.