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. Symbolically, the method of correspondence can be presented as: symbolically, the common method of concordance and difference can be presented as: it is important to remember that the application of the scientific method seeks to confirm or refute a hypothesis; However, this process should always be considered partial and provisional. The weight we will give to a confirmation or rebuttal is never all or nothing. We need to gather evidence over a long period of time. If we make mistakes, they are revealed by the results of repeated experiments. This principle, which is simply called the „common method“, simply represents the application of compliance and difference methods. As an example of the method of difference, we consider two similar countries. Country A has a center-right government, a unique system and was a former colony. Country B has a center-right government, a single system, but has never been a colony. The difference between countries is that country A gladly supports anti-colonial initiatives, while country B does not.
The difference method would identify the independent variable to be or not the status of each country as a former colony, the dependent variable supporting anti-colonial initiatives. This is due to the fact that, among the two similar countries compared, the difference between the two is whether they were once a colony or not. This then explains the difference with the values of the dependent variables, with the former colony supporting decolonization rather than the country with no history of being a colony. Symbolically, the method of accompanying variation can be represented as (with ± that represent a displacement): knowledge expands when we can verify or falsify a hypothesis. This is due to the fact that experimental tests are designed in such a way that the hypothesis is probably a generalized explanation of certain facts and not an isolated case. This type of experiment is controlled, which means that the experimental structures differ by only one variable (see Mills` difference method). 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. In this particular case, you are the only one who has not fallen ill. The only difference between you and others is that you didn`t eat a salad. This is probably the cause of other people`s illnesses.
This is an application of the method of difference. This rule states that if you have a situation that has one effect, and another that does not, and the only difference is the presence of a single factor in the first situation, we can deduce this factor as the cause of the effect. The accompanying variation method says that if we find in a number of situations leading to a particular effect, a certain property of the effect, which varies with the variation in a factor common to these situations, then we can deduce this factor as cause. The common method is to apply both the concordance method and the difference method as shown in the graph above. The application of the common method should therefore tell us that this time it is beef that is the cause. What prompted you to follow the method of the agreement? Please let us know where you read or heard it (including the quote, if possible). . . .