Some observers emphasize the fallacy involved in infering a further similarity from the recognition of a partial similarity between two instances. E.g. John Stuart Mill, A System of Logic: Ratiocinative and Inductive (Longmans, Green and Co., London, 1911), pp.520-525. Some explain reasoning by analogy in terms to two stages: perception and representation of a situation and then, comparison with the representation of another situation. See Douglas Hofstadter, Fluid Concepts and Creative Analogies: Computer Models of the Fundamental Mechanisms of Thought (Basic Books, New York 1995), p.180 . In contrast, some break down the analysis still futher, or emphasize the rule implicit in the case used for comparison with the disputed instance. See, e.g., Brewer, at 966:

"where x, y, z are individuals and F, G, H, are predicates of individuals:
 
Step 1: z has characteristics F, G, ...
 
Step 2: x, y, ... have characteristics F, G, ...
 
Step 3: x, y, ... also have characteristic H.
 
Step 4: The presence in an individual of characteristics F, G, ...
provides sufficient warrant for inferring that H is also present in
that individual.
 
Step 5: Therefore, there is sufficient warrant to conclude that H is
present in z. "