<prompt> Translate the following text to EnglishMfano wa kusudi: Mfano uliochaguliwa kwa usahihi kujibu maswali tofauti ya tathmini, kwa misingi mbalimbali ya utaratibu, kama vile mazoea bora au mabaya zaidi; sampuli ya hukumu.  <response>: Purposive Sample Instances appropriately selected to answer different evaluation questions, on various systematic bases, such as best or worst practices; a judgmental sample. 