 Dear students, today we are going to study Kuzai experimental designs in which we use both control groups and pre-tests. The basic design that we use when we have a control group and pre-test sample, in this we have one intervention group and another control group. In the intervention group, we do pre-testing and in the control group, we do pre-testing. So, the advantage of keeping a control group is that we can judge the selection bias in both the groups at the time of the pre-testing and the comparison we do after the intervention So, we can also judge whether there was any selection bias in the group selection. In this framework, the second design is that you have two pre-tests readings. So, the same pre-test is administered at two different time points, preferably with the same time delay as between the second pre-test and the post-test. So, in this, you have one experimental group and the other is a control group. And in this, you are taking two pre-tests and the interval of the time period of these pre-tests is as much as in the second pre-test and the post-test. So, why do we take two pre-tests in this? This is why we take it so that if there are any group differences, then we match it out and see that a particular group over the period of the time is behaving on a particular variable. And if there is a behavioral change in that, then is it being noticed in the control group or not? Then we conduct the intervention and then we conduct the post-test for both the groups. So, in this way, we have more possibility that we can monitor our behavioral change. Now, the third design is that we have a switching application of the treatment. We have two pre-tests and one post-test and two treatments at a different time period. So, what happens first is that both the treatment and the control group, at the start, we assume that they are pre-testing. Then our actual control group, we do not give treatment in that and our treatment group, we provide our treatment in that. And then the second pre-testing or post-testing, we can call it pre-testing and we can call it post-testing. Because there is a double treatment in this. So, at this level, the first treatment group becomes a control group and the control group becomes a treatment group. And then our now assumed treatment group gives our treatment and after that, we take post-test, third observation in both groups. So, what happens is that we see how our intervention is behaving in both groups. So, this design is a complicated design. For this, you obviously have a selection. You have this experimental design. So, the selection will be on a non-random basis only. But if there is a switching application of this kind of treatment, then the possibility is that we can monitor the selection bias in it and it becomes less. Now, the next design we have in that, we have pre-test and post-test by using reverse treatment. That is, we have two groups in this. We first do pre-testing of both groups. After that, we look at one treatment in reverse dimensions. For instance, here, X plus represents a treatment expected to produce an effect in one direction. And X negative represents a conceptually opposite treatment expected to reverse the effect. So, we look at a treatment in a positive direction. What is its impact? If the treatment is given negatively, then what is its impact? After that, we have a post-assessment of both groups. On the basis of this post-assessment, we look at the effect of the positive and negative treatment dimensions.