In other words the theoretical framework may be used by the researcher in order to explain the findings of his research which may raise new questions. This difference has implications for the probability distributions and the interpretation of the two test statistics. Experimental Probability The key difference between observational studies and experimental designs is that a well-done observational study does not influence the responses of participants while experiments do have some sort of treatment condition applied to at least some participants by random assignment. . Literary null a no difference form in terms of theoretical constructs. Operational null a no difference form in terms of the operation required to. After institutional review board approval and with written informed consent a controlled double-blinded study was conducted with 105 male and female patients ASA status I to III randomly assigned into 2 groups with the aid of a...