<P> The key issues in methods for historical comparative research stem from the incomplete nature of historical data, the complexity and scale of the social systems, and the nature of the questions asked . Historical data is a difficult set of data to work with due to multiple factors . This data set can be very biased, such as diaries, memoirs, letters, which are all influenced not only by the person writing them, that person's world view but can also, logically, be linked to that individual's socioeconomic status . In this way the data can be corrupt / skewed . Historical data regardless or whether it may or may not be biased (diaries vs. official documents) is also vulnerable to time . Time can destroy fragile paper, fade ink until it is illegible, wars, environmental disasters can all destroy data and special interest groups can destroy mass amounts of data to serve a specific purpose at the time they lived, etc . Hence, data is naturally incomplete and can lead social scientists to many barriers in their research . Often historical comparative research is a broad and wide reaching topic such as how democracy evolved in three specific regions . Tracking how democracy developed is a daunting task for one country or region let alone three . Here the scale of the social system, which is attempting to be studied, is overwhelming but also the complexity is extreme . Within each case there are multiple different social systems that can affect the development of a society and its political system . The factors must be separated and analyzed so that causality can be attained . It is causality that brings us to yet another key issue in methods for historical comparative research, the nature of the questions which are asked is attempting to propose causal relationships between a set of variables . Determining causality alone is a difficult task; coupled with the incomplete nature of historical data and the complexity and scale of the social systems being used to examine causality the task becomes even more challenging . </P> <P> The three identifying issues of historical comparative research are causal relationships, processes over time, and comparisons . As mentioned above causal relationships are difficult to support although we make causal assumptions daily . Schutt discusses the five criteria, which must be met in order to have a causal relationship . Of the five the first three are the most important: association, time order and nonspuriousness . Association simply means that between two variables; the change in one variable is related to the change in another variable . Time order refers to the fact that the cause (the independent variable) must be shown to have occurred first and the effect (the dependent variable) to have occurred second . Nonspuriousness says that the association between two variables is not because of a third variable . The final two criteria are; identifying a causal mechanism - how the connection / association among variables is thought to have occurred - and the context in which this association occurs . The deterministic causal approach requires that in every study, the independent and dependent variable have an association, and within that study every case (nation, region) the independent variable has an effect on the dependent variable . </P> <P> John Stuart Mill devised five methods for systematically analyzing observations and making more accurate assumptions about causality . Mill's Methods discusses; direct method of agreement, method of difference, joint method of agreement and difference, method of residues and method of concomitant variations . Mill's methods are typically the most useful when the causal relationship is already suspected and can therefore be a tool for eliminating other explanations . Some methodologists contend Mill's methods cannot provide proof that the variation in one variable was caused by the variation of another variable . </P> <P> There are several difficulties that historical comparative research faces . James Mahoney, one of the current leading figures in historical comparative research, identifies several of these in his book "Comparative Historical Analysis in the Social Sciences ." Mahoney highlights key issues such as how micro level studies can be incorporated into the macro level field of historical comparative research, issues ripe for historical comparative research that continue to remain overlooked, such as law, and the issue of whether historical comparative research should be approached as a science or approached as a history . This is one of the more prevalent debates today, often debated between Theda Skocpol, who sides with the historical approach, and Kiser and Hechter, who are proponents of the scientific view that should search for general causal principles . Both Kiser and Hechter employ models within Rational Choice Theory for their general causal principles . Historical researchers that oppose them (Skocpol, Summers, others) argue that Kiser and Hechter do not suggest many other plausible general theories, and thus it seems as though their advocacy for general theories is actually advocacy for their preferred general theory . They also raise other criticisms of using rational choice theory in historical comparative research . </P>

Who used historical comparative method in the study of west european societies