<prompt> Translate the following text to EnglishNi vigumu kuweka mipaka ya uaminifu juu ya NOEC na LOEC inayotokana na mtihani fulani, na ni vigumu kuhesabu usahihi wa mwisho wa NOEC na LOEC kati ya vipimo.  <response>: It is not possible to place confidence limits on the NOEC and LOEC derived from a given test, and it is difficult to quantify the precision of the NOEC-LOEC endpoints between tests. 