This paper presents a new statistical method that is well-suited to building and testing theories of change. An exploratory, robust two-way analysis of New Hampshire’s county-level presidential election returns for the past eighty years illustrates how this general technique can help to clarify theoretical concepts as well as to reveal systematic regularities in empirical data.
Because two-way analysis involves a number of novel techniques, this paper is primarily a methodological exposition. It devotes much more attention to step-by-step details of how the analysis was carried out, and the accompanying exhibits contain much more detailed information than normally would be the case for reporting results of such research.
In contrast to classical methods, the techniques presented in this paper are intended primarily for exploration of data rather than for statistical inference. They require very few assumptions about the data, and they are not unduly influenced by extreme or missing values. Graphic and semi-graphic devices keep the analyst close to the data and make it possible to display many numbers simultaneously in contrast to simple single-number summaries which can conceal information. Removing obvious regularities in the data facilitates discovery of other underlying patterns.