On an analog wattmeter, how accurate is the reading at full scale?

The accuracy of an analog wattmeter is highest at the full-scale reading because analog meters are designed to provide optimal performance within the limits of their range. When the meter is used at or near its full scale, the mechanical components and the calibration of the meter give the most reliable readings.

At this point, the needle is moving through its optimal range, and variables such as parallax error become minimized because the measurement is distinctly defined. While it can give readings across its entire scale, the potential for inaccuracies increases as you move away from the full-scale mark, typically due to factors like meter sensitivity and resolution. Thus, the assertion that accuracy extends from full scale to the rest of the range suggests a misunderstanding of how analog meters operate; they are not linear in accuracy throughout their entirety.