Consider as an example of the two similar countries difference method. Country A has a centre-right government, a uniform system and was a former colony. Country B has a centre-right government, a single system, but has never been a colony. The difference between countries is that Country A easily supports anti-colonial initiatives, while country B does not. The difference method would or would not identify the independent variable as the status of each country as a former colony, the dependent variable supporting anticolonial initiatives. This is because the two similar countries have compared, the difference between the two is whether they were previously a colony or not. This then explains the difference with the values of the dependent variables, the former colony supporting decolonization rather than the country without a history of being a colony. Although Mills` methods are an important part of the serious study of natural phenomena, they have significant constraints. These methods can only be applied with care if all relevant pre-gonal circumstances are taken into account, which cannot be guaranteed in advance. Mills` rule of understanding states that if, in all cases where an effect occurs, there is a single prior C factor 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 oysters.
Therefore, if we apply the rule of concordance, we conclude that the consumption of oysters is the cause of the disease. Under the tailings method, if we have a number of factors that are assumed to be the causes of a number of effects, and we have reason to believe that all factors, with the exception of a factor C, are causes of all effects, with the exception of one, we should infer that C is the cause of the residual effect. Mills` methods are five methods of induction described by the philosopher John Stuart Mill in 1843 in his book A System of Logic.  They must shed light on issues of causation. Even simply referred to as the “common method,” this principle represents only the application of methods of concordance and difference. Mills` methods can only reveal evidence of probable causes; they don`t really offer an explanation. The discovery of causalities is an important step towards understanding the world, but it is only part of what we need. We also need to understand how and why some cases of causation work the way they do. The answers to these questions lead us to the possibility of identifying cause-and-effect relationships. We need to develop theories and hypotheses that underpin the scientific argument. It is important to remember that the use of the scientific method attempts to confirm or disprove a hypothesis; However, this process must always be considered partial and temporary.