anchor: In any case, he observed, even in the existing randomized trials of interventions that use motivational interviewing, we cannot evaluate the effect of counselors' skill levels.
positive: He observed that in the randomized trials of interventions that used motivational interviewing, we can't see how skilled the counselors are.
negative: He observed that in the randomized trials of interventions that used motivational interviewing, we must look at  how skilled the counselors are in comforting patients.