ruggedness
/ RUG-id-ness /
A reliable car starts whether it is freezing or sweltering, whoever turns the key, on the cheap fuel or the premium. A temperamental car only behaves for its one owner in mild weather. Ruggedness is that dependability for an analytical method: does it still give the same answer when the everyday surroundings change — a different analyst, a different instrument, a different day or a different lab?
Ruggedness is the degree to which a method's results stay reproducible under the normal, larger variations of real practice: different operators, instruments, reagent lots, laboratories and time. It is tested by deliberately running the same samples under these changed conditions and seeing how much the results spread. A rugged method gives closely matching answers across all of them.
It matters because a method that only works for its inventor on a good day is useless in the wider world, where it must travel between people and places. The honest caveat is that ruggedness and robustness are close cousins that different guidelines define slightly differently; the practical point is the same — a method must survive being handled by ordinary people under ordinary, changing conditions.
To test ruggedness, a method for vitamin C in juice is run by three different analysts on two instruments over a week; all twelve results agree within 3% of each other, confirming the method travels well between people and machines.
Same samples, different people and machines — and the answers still agree.
A common convention treats robustness as resistance to small deliberate changes within one lab, and ruggedness as performance under larger, real-world changes such as different analysts and labs; the latter overlaps strongly with intermediate precision and reproducibility.