Cal-lab slang for the divisor of about 1.732 applied to the half-width of a rectangular distribution to convert it to a standard uncertainty. Techs talk about root-threeing a spec, or ask whether a line is root three or root two when checking which distribution a budget assumes. The sibling divisors are root six for triangular, root two for U-shaped and the coverage factor for normal certificate values.
It's a spec limit, root three it and move on, don't treat it like it came off a cert.
Also heard as
- root-three it
- divide by root three
Related terms
Rectangular distribution
A distribution giving equal likelihood to every value between two limits, used when only the bounds are known.
Triangular distribution
A distribution peaked at the center and falling linearly to zero at the limits, with a divisor of root six.
U-shaped distribution
A distribution where values near the limits are most likely, used for cycling effects such as RF mismatch or room temperature.
Type B evaluation
Sizing an uncertainty component from existing knowledge such as certificates, specs or resolution, with no new repeat data.