Yarn quality requirement is changing everyday. Quality requirement is different for different end uses and it is different for different customers. It is easy to make the highest qulity yarn just for the sake of achieving the best yarn results. But it is difficult to produce a good quality yarn with a minimum deviations. Very high fluctuation in yarn quality is an EVIL for any enduse. Some times it is better to keep same level of yarn quality ( around 25% USTER STANDARDS) by strict quality control than achieving 5% USTER STANDARD but without consistency. Consistent quality will be very much appreciated by the clients.

"I often say that when you can measure what you are speaking about and express it in numbers, you know something about it. But when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meagre and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the stage of science, whatever the matter may be" (attributed to Lord Kelvin, 1883).