<prompt> Which of the following is not true about non-randomized trials?Approach of comparability is highDegree of comparability is highThe experiment can serve as its own control or can utilize a natural controlSeveral trials may be needed before evaluation is considered conclusive  <response>: Non-randomized trials i.e. Those depaing from strict randomization for practical purposes but in such a manner that non-randomization does not seriously affect the theoretical basis of conclusions refer pg 81, park 23 rd edition 