The Logic of Comparative Research

In this part of the course we will discuss various strategies of comparative research:
First, Mill's distinction between two types of comparative research: The Method of Agreement and the Method of Difference;
Second, we will distinguish between Most Similar and Most Different Systems research designs


Mill's Method of Agreement and Method of Difference

Mill's methods are of particular importance to comparative studies: the method of agreement and the method of difference. Read the following texts (make sure that you have a password):

1. Mill's Method of Agreement [HTML format] OR in Microsoft Word Format

2. Mill's Method of Difference [HTML format] OR in Microsoft Word Format

3. You may also want to read extracts from Mill's original text on two Methods of Comparison (optional)


The Method of Agreement: the study of similar cases in order to find their causes

The Method of Difference: the study of contrasting cases in order to find their causes.

The major difference between these two methods is that the method of difference uses negative cases to reinforce conclusions drawn from positive cases (that is, from cases of agreement).



Most Similar and Most Different Systems

read on : Research Design and Case Selection (HTML FORMAT) or,
(Rich Text Format (WORD) (make sure that you have a password)

A Most Similar System Design compares similar cases as possible on the assumption that the more similar the cases being compared, the more possible it should be to isolate the factors responsible for differences between them.

A Most Different System Design compares as contrasting cases as possible in order to show the robustness of a relationship between dependent and independent variables. Such a design assumes that by demonstrating that the observed relationships hold in a range of contrasting settings the argument of the research is better supported









Four types of Comparative Research Designs

Method of Difference

Method of Agreement

Most Similar System
Research Design
Example 1

Barrington Moore's Study of the differences between Democratic and undemocratic Routes to Modern Society

(dealing with differences in Similar Cases)

Example 2

Barrington Moore's Study of the Democratic Routes to Modern Society

(dealing with similarities in Similar Cases)

Most Different System
Research Design
Example 3

Tocqueville's Study of Democracy in America by comparing it to France

(dealing with differences in Different Cases)

Example 4

Skocpol's Study of the French, Russian and Chinese Revolutions

(dealing with similarities in Different Cases)

Read, Faure M. Andrew, "Some Methodological Problems in Comparative Politics", Journal of Theoretical Politics, Vol. 6, No. 3, 1994, pp. 307-322. Especially pp. 310-318.


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