Symbolically, the method of accompanying variation as (with Â± that represents a displacement): The method of the variation that accompanies it is that, in a number of situations that lead to a particular effect, we find a certain characteristic of the effect that varies with variation in a factor common to these situations, then we can deduce this factor as a cause. Mill`s Methods are five methods of induction described by the philosopher John Stuart Mill in his book A System of Logic, published in 1843.  That they shed light on questions of causality. Mills` rule of conformity states that if, in all cases where an effect occurs, there is only one preceding C factor that is common to all of these cases, then C is the cause of the effect. According to the table in this example, the only thing you ate was the oyster. This type of experiment is controlled, which means that the experimental structures differ by only one variable (see Mills` difference method). The experimental group is the one that receives the variable, while the control group does not. For a property to be a necessary condition, it must always be present when the effect is present. As is the case, it is in our interest to examine cases where the effect is present and to take into consideration the properties present and those that are considered as “possible necessary conditions”. Obviously, not all properties missing when the effect is present can be necessary conditions of action. In comparative politics, this method is more generally referred to as the most diverse system design. .