<prompt> Translate the following text to EnglishKatika utafiti wake wa vituo vingi, waingiliaji walijisikia wamezuiliwa na uingiliaji wa kawaida, wakihisi kwamba tofauti ilihitajika ili kukidhi mahitaji tofauti ya wateja.  <response>: In his multi-center study, interventionists felt restricted by a standard intervention, sensing that variation was needed to meet different clients needs. 