“Whereas probability reflects the likelihood that a statement is true, analytical confidence reflects the soundness and stability of the foundations on which the assessment of likelihood has been made.”Professional Head of Intelligence Assessment (PHIA), Guvernul Regatului Unit · Explaining Uncertainty in UK Intelligence Assessment · 2025 · PHIA, «Explaining Uncertainty in UK Intelligence Assessment» (GOV.UK, publicat pe 24 martie 2025), secțiunea «Analytical Confidence Rating (AnCR) Framework»
Missing evidence lowers confidence, not probability.
These are two different questions: how likely the event is, and how solid your basis for saying so is. You can judge an attack likely on the strength of a single new source — high probability, low confidence — or unlikely on ten years of consistent data — low probability, high confidence. The British guidance grades analytical confidence (the Analytical Confidence Rating) as one of three levels — high, moderate, low — against three criteria: information base, analytical rigour, and complexity and volatility. Confidence also tells the reader how easily the judgement might change. The practical rule: express probability with a word from the scale, and explain confidence separately, with its reason — which source is missing, what could change the picture. ICD 203 goes down to grammar: a product using a confidence level must not combine it with a degree of likelihood in the same sentence. The reason is a phrase such as we have high confidence that it is unlikely, which the reader hears as a single number. The trap: lowering the probability when what you really lack is evidence. Missing evidence lowers confidence; it does not automatically move the event towards unlikely.
The card says the two axes are written separately. The next step: confidence is also a signal about durability. A probability describes the world today. High confidence says the judgment would survive new information. Low confidence is a warning: the first contrary report could overturn it. That is why a smart reader asks not only how likely something is, but how long the answer can be relied on. Example: a doctor who says the tests most likely show a routine infection, but admits she has only seen the first results. The prognosis may be right, yet a retest tomorrow is warranted. The UK guidance asks for exactly this: alongside the rating, the reason — which source is missing, what could change the picture. Next step: what to do concretely when confidence is low but the decision cannot wait.
Why it matters A decision-maker given only the probability cannot tell whether the judgement will hold until tomorrow or flip at the next report.