Era 10 / 15 · Statistical AI 1990s–2000s

Statistical AI

From hand-rules to probability and data — let the numbers decide.

Beat 1 · Concrete

A belief that sharpens

A wide guess about a hidden value; each datum slides and tightens it toward the truth.

Belief sharpening A wide low coral curve of uncertainty and a narrow tall green peak both shown over a hidden true value marked in teal. wide guess truth

Beat 2 · Abstract

Prior × likelihood

Same mechanism, stripped: a prior, multiplied by each datum's likelihood, gives a tighter posterior.

Bayes rule as curves A broad sand prior times a coral likelihood yields a narrow green posterior centered on the truth. prior likelihood posterior

Beat 3 · Interactive

Add data, watch it tighten

Click to add observations. More data narrows the posterior around the true value.

More data, less uncertainty A narrow green posterior pinned on the teal true value after many observations. truth
data: 0 · uncertainty: wide
Field notes · the statistical turn
1988
Bayesian networks
Judea Pearl gave probability a graph: nodes are variables, edges carry belief that propagates as evidence arrives.
Speech
HMMs & SVMs
Hidden Markov models drove speech recognition; kernel methods and support-vector machines won on the margin.
Jelinek
"Fire a linguist"
"Every time I fire a linguist, the system gets better." Data and statistics outran hand-written rules.