One estimate, with room around it

Suppose 40 of 61 historical observations meet a definition, giving a rate of about 65.6%. That is the centre of the story, not the whole story. A 95% Wilson interval for this example runs from roughly 53% to 76%.

The interval makes a practical fact visible: the sample supports more than one exact underlying rate. Values near the middle fit more comfortably than the headline alone suggests, while values outside the range fit less comfortably under the method's assumptions.

What 95% refers to

A frequentist 95% confidence interval is produced by a procedure designed to cover the true parameter in about 95% of repeated comparable samples. Once one interval has been calculated, the parameter is not repeatedly moving in and out of it.

In ordinary product language, it is reasonable to call this a plausible range under the stated method, provided we do not turn it into a guarantee. Different models and assumptions can produce different intervals from the same observations.

Why intervals widen and narrow

Small samples usually produce wide intervals because many underlying answers remain compatible with limited experience. Larger informative samples tend to narrow them. A rate close to the middle of its possible range may also behave differently from one close to zero or one hundred per cent.

A narrow calculation can still be misleading if the sample is biased or observations are strongly connected. The interval describes sampling uncertainty within the model. It does not automatically include every source of error in the research process.