55 A fit cannot be extended beyond its points

What people usually ask

Fit a curve to these six points and give me the value at 25 L/min.

What comes back

A fitted curve and a single number at 25 L/min, read off a line that has no point past 12.

Ask this instead

Six measured points, pressure drop in kPa against flow in L/min
on one filter housing: (2, 0.9), (4, 3.1), (6, 6.8), (8, 12.4),
(10, 19.0), (12, 27.9).
Fit dp = a * q^n by least squares on the logs. Report a and n
with a 95 percent interval for each and the residual at every
point. Plot the points and the fitted curve from 2 to 12 only,
nothing beyond 12.
State the range the fit covers as "2 to 12 L/min".
Do not give a value at 25 L/min from this fit. Say in one
sentence why: the six points say nothing about the housing
between 12 and 25, and the exponent may change there.
If a value at 25 is needed, offer a separate route that uses
neither the fitted a nor n: the maker's published curve for the
housing, or a new measurement at 20 and 25. Stop there.

Attach: The six points, in the prompt or as a two column CSV.

Why it works: The refusal is asked for in advance with its reason, so the fit reports what it covers and is not stretched to answer a different question.