Statistical predictions are based on groups, and the things that might happen to them, and the supposedly hidden connections among those things. As David Berreby points out, statistical efforts are forward-looking. This is what they ask: "What is likely to happen in the future? Or, What would happen in the future if this hypothesis were true? These two modes of thinking about experience are truly incompatible."
Despite this problem, Berreby argues that we "persist in trying to turn statistically-based estimates about future results into narratives." Our brains have evolved this way. "So people who want to make statistical points about people in general will instinctively brighten up their picture with some compelling story—either hypothetical (imagine a 20-year-old schizophrenic being cared for by a demented old father!) or concrete (this guy had a leg amputated due to diabetes!)," Berreby points out.
Narrative, in other words, is intended as an illustration of a statistically-based argument: "In the first, it's "you should have children earlier in life than you imagine"; in the second, it's "you should drink and eat less sugar."