Methods for Combining the Idiographic and Nomothetic Approaches in Personality

1. Methods for Combining the Idiographic and Nomothetic Approaches in Personality Kimberly K. Assad, Gustavus Adolphus College & James W. Grice, Oklahoma State University RESULTS (CONT.) ABSTRACT METHOD idiographic grids. Again, isotropic and centering scaling options were applied, and the resulting consensus proportion was only .44, suggesting a relatively low degree of agreement among the students’ views of one another when permitted to use their own personal constructs. The result was still statistically significant according to a randomization test (p < .01). An exploratory Principal Component Analysis was conducted on the idiographic consensus grid to uncover the major dimensions of discrimination among the 25 rated students. The results produced two strong components that accounted for 56% of the variation in the consensus grid values. These two components were transformed using promax rotation and then mapped into the Big Five component space of the nomothetic consensus grid using extension analysis. The results showed that 92% of the variance in the first component overlapped with the Extraversion Big Five component, and that 56% and 55% of the variance in the second component overlapped with Agreeableness and Conscientiousness, respectively. These two components were correlated .61. The two major dimensions of commonality among the idiographic ratings thus corresponded largely to Extraversion, Agreeableness, and Conscientiousness. A two-dimensional plot of the Extraversion and Agreeableness components computed from the nomothetic (Big Five) consensus grid can be seen in the left panel of Figure 1. Shown in right panel of Figure 1 is a two-dimensional plot of the first two rotated components from the idiographic consensus grid. Examination of the two graphs shows a high degree of consistency in the patterns of the rated students. For instance, in the nomothetic plot the Ideal self, Josh, and Trish are viewed as the agreeable extraverts whereas Don, Sue, and Jill are viewed as the disagreeable introverts. Nearly the same organization can be seen in the idiographic plot. Using Slater’s coefficient of congruence, the degree of pattern similarity between the rated students in the nomothetic and idiographic grids was in fact high, .76. The idiographic andnomothetic approaches to personality assessment were empirically combined in a recent study by Grice (2004). In the current study, we employed and extended the analyses used by Grice in a study of twenty high school students participating in a 1-week Summer Science Academy. The students first completed an idiographic task in which they rated themselves, their ideal selves, and the other 24 students in the program on their own, unique personal constructs. They then completed a nomothetic task in which they rated the same people on marker items for the Big Five personality traits. Multiple group components and extension analyses indicated that the Big Five ratings explained approximately 55% of the variation in the idiographic ratings. Results from a Generalized Procrustes Analysis yielded consensus grids (essentially re-scaled and rotated average grids) for the idiographic and nomothetic ratings. The empirical overlap between the configurations of the people in the two consensus grids was found to be approximately 76%. The results were generally consistent with those reported by Grice, and showed that the idiographic and nomothetic approaches to personality assessment can be empirically and meaningfully combined. The results also showed that the Big Five and personal construct ratings overlapped to some degree, yet also yielded distinct information. Idiographic grid.Each participant was initially handed a sheet containing both labeled pictures of 21 students in the Summer Science Academy, and 4 spaces to induce cues of the 4 students who were not pictured, to help each participant remember the other students. Each participant was taken individually into a private workspace to complete the experiment. The “ideal self” and the names of the 25 students were entered into version 2.3 of Idiogrid (Grice, 2002) – software for managing and analyzing repertory grids and other types of self-report, personality data. The participants were then administered a sentence completion task developed by Grice, et al. (2004) to elicit their bipolar personal constructs. For instance, the participants were required to complete the following sentence with a single word or short phrase: “Generally speaking, I am the type of person who is ________ .” After entering a response, the participants were then immediately asked to enter the opposite word or phrase, thus yielding a bipolar personal construct. After eliciting the 10 personal constructs, participants rated (in random order) each of the 26 elements (viz., ideal self, and 25 individuals, including themselves) on each construct using a 5-point Likert-type scale ranging from “Very Inaccurate” to “Very Accurate.” Each item stem was displayed as “____ is the type of person who is ____” (as opposed to ___). The first blank contained the element being rated, and the other 2 blanks contained the poles of a personal construct. The 260 ratings were placed in a 10 x 26 (constructs x element) matrix, or grid, for further analysis. Nomothetic grid. The 26 elements from the idiographic grids were loaded into the nomothetic grids in Idiogrid. The participants then rated each of the 26 elements on 20 Big Five trait descriptors. The descriptors were selected from Goldberg’s list of 100 lexical marker items (Goldberg, 1999) and altered slightly to fit the item stems. Four items were selected for each of the Big Five Personality traits, with two of the four items for each trait being reverse-keyed. Each element was then rated (in random order) by each participant on the same 5-point Likert scale. Each item stem was presented as “____ is the type of person who is ­­­____.” The first blank contained the element being rated, and the second blank contained the Big Five descriptor being considered. The 520 ratings were placed in a 20 x 26 (Big Five descriptor traits x elements) matrix, or grid, for subsequent analysis. INTRODUCTION Ever since Gordon Allport first began examining the differences between the nomothetic and idiographic approaches to personality in 1937, there has been much debate over which approach is best. The former approach relies primarily on aggregate methods of data collection and analysis, such as factor analysis or multidimensional scaling, to discover broad constructs that summarize inter-individual differences. The latter approach, by comparison, relies on methods of data collection and analysis that place considerably more emphasis on intra-individual information. While the nomothetic and idiographic approaches to personality are different, they are not exclusive. Some scholars have argued that to fully grasp the entirety of personality, both the nomothetic and idiographic approaches must be used together (Grice, 2004; Kelly, 1955; Rosenzweig & Fisher, 1997; Runyan, 1983). The general laws of personality and the particular cases of personality are related since the general laws are obtained through the study of individuals. For example, once an individual displays a novel personality trait, that trait can then be assessed in other people (Runyan, 1983). This transformation from an idiographic approach to a nomothetic approach illustrates the strengths of each method. The nomothetic method can make generalizations to a population, but cannot particularize to specific individuals. Contrarily, the idiographic approach can particularize to an individual but cannot make generalizations about a population (Runyan, 1983). Additionally, the idiographic approach helps to clarify the nomothetic approach because nomothetic traits must be tested at the individual level. In his 2004 study, Grice devised an approach to empirically combine the nomothetic and idiographic assessment strategies. Specifically, he asked participants to rate themselves and other known individuals on marker items for the Big Five personality factors and on their own, unique personal constructs. Grice then used a simple type of confirmatory components analysis to compare the two sets of ratings. Results indicated that approximately 51 percent of the variance in individual personal construct ratings overlapped with the Big Five ratings. Thus, while the Big Five factors accounted for a slight majority of the variance in the personal construct ratings, nearly half of the variance was outside of their purview. In the current study we utilized the methods developed by Grice to compare ratings obtained from high school students attending a 1-week Summer Science Academy at Oklahoma State University. These students shared a common living space and participated in numerous activities over the course of the academy. At the end of the week we asked the students to rate themselves and the other students on marker items for the Big Five personality factors and on their own personal constructs. Unlike Grice’s previous study then, the same individuals were rated nomothetically and idiographically by the participants in this study. Consequently, we were able to run a unique set of analyses (viz., Generalized Procrustes Analyses) to explore the commonality between the nomothetic and idiographic ratings. RESULTS Multiple Group Components and Extension Analyses The fit of the Big Five components to the individual nomothetic grids was assessed using Multiple Group Components Analysis (MGCA), a simple form of confirmatory components analysis. The mean eigenvalues across all participants indicated that the five components were relatively equal in strength, and the mean of the item communalities (M = .69, SD = .12) indicated that most of the variance in the Big Five marker items was explained by the five components. The overall fit of the Big Five model was assessed by computing the proportional change between the Root Mean Square values for the original and residual correlation matrices for each participant’s grid. The average proportional change across all grids was .70 (SD = .15). These statistics indicate that the five components explained approximately 69 to 70 percent of the variance in the ratings on the twenty Big Five marker items. Lastly, the correlations among the five components were, on average, moderate in absolute value (M = .46, average Mdn = .46, average SD = .18). The degree of overlap between the nomothetic and idiographic grids was then assessed with extension analysis. Specifically, each participant’s personal constructs were mapped into the five-component space derived from the MGCA. The mean item communalities were then calculated for the personal constructs in order to determine how well the Big Five Personality components explained the variation in the personal construct ratings. The mean value computed across all constructs and all grids was found to be .55 (Mdn = .56, SD = .11). These results indicate the Big Five components explained only a slight majority of the item variance, and a large portion of the variance was left unexplained. Consequently, the participants’ personal constructs did not fit completely within the Big Five component space. This finding is reinforced by the degree of similarity between the idiographic and nomothetic grids as measured by the coefficient of congruence (Slater, 1972). The grids yielded a mean coefficient of .44 (Min = -.10, Max = .79, Mdn = .51, SD = .26), which was somewhat lower in magnitude than the value (.53) reported by Grice (2004). A value equal to 1.0 would indicate perfect overlap between the two grids. Generalized Procrustes Analysis A Generalized Procrustes Analysis (GPA) was conducted on the nomothetic grids. Isotropic and centering scaling options were applied to the grids as part of the analysis (see Grice, 2004, p. 14). GPA yields a consensus grid, which is essentially an average grid derived from rotated, re-scaled versions of the original nomothetic grids. The GPA also yields an index of consensus among the nomothetic grids based on their similitude with the consensus grid. This consensus proportion, which can range in value from 0 to 1, was .54 and indicated a moderate degree of agreement among the students’ views of one another on the Big Five marker items. The result was also statistically significant according to a randomization test (p < .01; Wakeling, Raats, Halliday, 1992). A GPA was next performed on the CONCLUSIONS • The primary conclusions of this study were as follows: • 1. The Big Five Model fit the individual nomothetic grids (ratings of self and others on marker items for the Big Five) reasonably well. • 2. Extension analysis and Slater’s coefficient of congruence indicated that, at best, 50% of the variance in the idiographic grids (ratings of self and others on participants’ unique personal constructs) overlapped with the nomothetic grids. • 3. Generalized Procrustes Analysis indicated modest agreement among the participants’ nomothetic and idiographic ratings of themselves and the other students in the Summer Science Academy. • 4. The commonality that did exist among the participants’ personal constructs was determined to be primarily Extraversion and secondarily Agreeableness and Conscientiousness. • 5. Person-centered analyses that blend the nomothetic and idiographic traditions are fully possible, and these methods may prove useful in developing a more complete model of personality. PARTICIPANTS CONTACT INFORMATION Twenty-five high school students participated in the 2004 Summer Science Academy at Oklahoma State University, a program designed for Oklahoma high school students with the intention of developing mathematical and scientific cognitive skills. Of these students, twenty (5 males, 15 females) voluntarily participated in this study. Participants ranged in age from 13 to 16 years (M = 14.55, Mdn = 14.00, SD = 1.10) and were obtained from across Oklahoma. Six participants were Caucasian, 4 were African American, 7 were Asian, 2 were Native American, and 1 was Hispanic. All participants were tested individually on computers, and did not take longer than 2 hours to complete the experiment. All participants completed the tasks described below only after having a parent or guardian complete a consent form. Inquiries, including requests for a complete list of references can be obtained from Kimberly Assad at: kassad@gac.edu. Inquiries can also be sent to James W. Grice, Ph.D., at: jgrice@okstate.edu. You can also visit the Personality Research Laboratory at OSU: http://psychology.okstate.edu/faculty/jgrice/personalitylab/