Personal Construct Theory
The Repertory Grid is a data extraction and analysis technique that has as its basis the Personal Construct Theory, which George Kelly developed in the 1950s. The central theme of the Personal Construct Theory is that people organize their experiences with the world into conceptual classifications that we can differentiate and describe using attributes of those classifications called constructs. Often, these constructs manifest themselves as polar opposites on a scale, so we can easily classify the elements of our world. For example, based on our experiences with people, we know that some are shy and others are outgoing. When we meet new people, we may consciously or subconsciously categorize them according to that construct.
An important element of the Personal Construct Theory is that each individual has his or her own unique set of constructs that are important to that person. Taking my example further, whether a new person is shy or outgoing might not be important to you in your categorization scheme, but it might be very important to someone else. George Kelly hypothesized that people are constantly challenging and growing their construct systems, but those systems remain unique to the individual, and the sum of each person’s experiences shapes them. In addition, the differences in people’s construct systems contribute to our different perceptions of the world and our behavior in it.
For example, when choosing a place to live, one person might organize her choices using a construct that rates locations according to how easy it is to get to work, because she’s experienced tough commutes in the past. Another person might organize his choices by climate or some other factor. According to the Personal Construct Theory, each person has his or her own unique system and prioritization of constructs, or way of construing the world.
It is this inherent difference in construct systems between people that introduces bias in research: The researcher has one set of constructs, and each participant has another. Especially in survey or structured-interview research, a researcher might ask questions he feels are important. Participants can answer those questions, but are they really the most relevant questions? For example, in evaluating the user experience of a Web site, we can ask participants whether they think the site is trustworthy and why. Each participant might be able to answer these questions, but is a trustworthy site important to that participant for that domain?
Even the most well-intentioned researcher, drafting questions that are as open-ended and unbiased as possible, still might lead some participants down an irrelevant path. Kelly developed the Repertory Grid as an interview technique that attempts to minimize the construct bias of the interviewer and systematically extract constructs for a particular domain that are important to participants. Why is it called the Repertory Grid? First, Repertory comes from the word repertoire, which refers to a participant’s repertoire of constructs. The Grid refers to the data extraction and analysis procedure researchers use to gather and compare information from a number of participants in a study.
The Repertory Grid Process
Traditionally, researchers conduct a Repertory Grid study by choosing several examples in a particular domain with which participants interact. Ideally, there will be 6–12 different examples that represent a wide variety of approaches and potential constructs. A Repertory Grid study then proceeds according to the following four general steps:
- selection—During each session, either the participant or the researcher chooses to work with three random examples from the initial set. (Ideally, there are multiple participants in the study, and each participant works independently, with a different set of examples.)
- triading—This is the core aspect of eliciting constructs without introducing bias from the researcher. The researcher asks the participant to identify how two of the three examples are different from the third. The researcher does not provide a starting point, but just asks the participant about the constructs that are important from his or her perspective. Often the constructs that are most important to the participant are surprising—and sometimes not related to the topic that the researcher intended. However, this is the key aspect of the exercise—to uncover what is important to the participant.
Once the participant identifies a construct, or how two of the examples are different from the third, the participant names the two polar opposites of the construct, identifies which is good and which is bad, then writes the names of its two contrasting poles at the opposite ends of a row in the grid.
The participant continues the process of triading examples to identify additional constructs for the domain. Participants can change which two examples are alike and which are different for different constructs. The key is to elicit as many constructs as possible, without any suggestions from the researcher. The researcher can ask probing questions and ask the participant to think aloud, but suggesting dimensions for constructs introduces the bias that this method seeks to avoid.
- rating—After identifying and naming the contrasting poles for constructs during the triading step of this process, the participant rates all of the original examples in the study—that is, the 6–12 examples, including the three the participant used in triading—basing his or her ratings on the constructs the participant developed during triading. For each individual construct, the participant rates an example on a scale of 1 to 5, where 1 represents one end of the pole and 5 represents the other.
For example, if a participant identified a construct with the two poles organized and cluttered, the researcher would ask the participant to rate each example on a scale from 1 to 5, where 1 is organized and 5 is cluttered.
Depending on the number of examples and constructs the participant identified during the triading step, this rating process can take some time, so be sure to allow for it in your scheduling.
- analysis—You can analyze the results of a Repertory Grid study both qualitatively and quantitatively. Often, a qualitative analysis is enough to develop a good understanding of the constructs that are important to the target audience. By reviewing notes from the triading sessions and conducting affinity diagramming sessions to assess the various participants’ constructs and language, researchers can identify themes that can inform their decision making for the domain. In addition, to statistically identify which constructs are most relevant and most clearly distinguish the selected examples, a researcher can apply factor analysis to the participants’ ratings of the examples. The result is a dendrogram or tree diagram like that shown in Figure 1, which is similar to what you would get during a card sort exercise and shows
- which examples are most closely associated with one another
- the selected examples’ most differentiating characteristics