<prompt> Translate the following text to SwahiliA valid cause-and-effect design-that is, one with internal validity-rules out alternative explanations of results by comparing what happened with an intervention to what happened in the absence of the intervention.  <response>: Muundo halali wa sababu na athari - yaani, moja na uhalali wa ndani - hukataa maelezo mbadala ya matokeo kwa kulinganisha kile kilichotokea na uingiliaji na kile kilichotokea bila uingiliaji. 