<prompt> Translate the following text to EnglishKwa ujumla, wachunguzi waliopewa kazi ya kufanya tathmini za mapema za masomo ya kesi walikuwa wamefundishwa katika taaluma za kitaaluma zilizo na mapokeo ya kazi ya shambani yenye nguvu zaidi, na walilazimika kupambana na kiwango ambacho mbinu yao ya utafiti inaweza kubadilishwa kwa tathmini, kudumisha uadilifu wake, na kutoa faida chanya.  <response>: By and large, investigators commissioned to carry out the early case study evaluations had been trained in the academic disciplines with the strongest fieldwork traditions, and they had to struggle with the extent to which their research method could be adapted to evaluation, retain its integrity, and yield positive benefits. 