<prompt> Translate the following text to EnglishKatika mazoezi, usahihi wa matokeo ya vipimo vya mara kwa mara ni kuchukuliwa kukubalika kama NOECs kutofautiana kwa zaidi ya moja mkusanyiko kati ya juu au chini ya mwelekeo wa kati.  <response>: In practice, the precision of results of repetitive chronic tests is considered acceptable if the NOECs vary by no more than one concentration interval above or below a central tendency. 