The linkage between constitutionalism and political culture is not always directed, fixed, or clear, however it depends upon which method of comparison is adopted. While studying comparative approach the unubiquitous issue present now a days is the political comparison of umpteen countries, which most closely approximates the experimental method of science. This comparison is particularly suited to quantitative analysis through measurement and analysis of aggregate data collected on many countries (Lijphart 1971). Although there are examples of qualitative comparisons of such countries, like Huntington's (1996) The Clash of Civilizations and Finer's (1997) History of Government, the majority of studies that compare many countries simultaneously use quantitative methods. This method of comparison requires a higher level of abstraction in its specification of concepts in order to include as many countries as possible. (Landman, 2003) Its main advantages include statistical control to rule out rival explanations, extensive coverage of countries along with its political circumstances, the ability to make strong inferences, and the identification of 'deviant' countries or 'outliers'.
Comparing many countries is referred to as 'variable-oriented', since its primary focus is on general dimensions of macro-social variation (Ragin, 1994) and the relationship between variables at a global level of analysis. The extensive coverage of countries allows for stronger inferences and theory building, since a given relationship can be demonstrated to exist with a greater degree of certainty. For example, Gurr (1968) demonstrates that levels of civil conflicts across 114 countries are positively related to the presence of economic, political, short-term, and long-term deprivation. His analysis also explains that this relationship holds for roughly 65 per cent of the countries. More recently, Helliwell (1994) has shown that for 125 countries from 1960-1985 there is a positive relationship between per capita levels of income and democracy. After controlling for the differences between OECD countries, Middle Eastern oil-producing countries, Africa, and Latin America, this relationship is demonstrated to hold for about 60 per cent of the countries.
A second advantage of comparing many countries lies in the ability to identify so-called 'deviant' countries. These are countries whose values on the dependent variable are different than expected, given the values on the independent variables (levels of deprivation or per capita income). In testing for the positive relationship between income inequality and political violence in sixty countries, Muller and Seligson (1987) use a simple scatter plot to identify which countries fit their theory and which do not. For example, Brazil, Panama, and Gabon were found to have a lower level of political violence than was expected for the relatively high level of income inequality. On the other hand, the UK was found to have a particularly high level of political violence given its relatively low level of income inequality. By identifying these 'outliers', scholars can look for other explanations that account for their deviance, and they can remove them from their analysis to make more accurate predictions for the remaining countries. (Landman, 2003)