Bootstraps taxometrics: Solving the classification problem in psychopathology

“(Meehl, 1995, p. 269) In this section we propose a taxonomy of the various dimensions along which studies may be organized, explain why these dimensions were chosen, discuss possible interactions between dimensions, and apply the taxonomy to the transfer literature.”

“Instead, these authors used taxometric techniques developed by Meehl and his colleagues (Meehl, 1995).”

“MAXEIG is a multivariate extension of Meehl and Yonce’s (1996)”

“…generating model, and because each model can equivalently reproduce the covariances, it could be argued that neither model is superior to the other (i.e., Cudeck & Henly, 2003; B. Muthén, 2003), though we do not necessarily take this view ourselves (Bauer & Curran, 2003b; see also Meehl, 1995).”

“To do so, we relied on taxometric analyses [52–56], procedures that determine if relations among observed data are better accounted for by the presence of dimensional or categorical latent structure.”

“Meehl and his colleagues (e.g., Meehl, 1995; Waller & Meehl, 1998) have devised a methodological approach for exploring the latent structure of psychological constructs.”

“Lacking such specification, we are forced to infer psychopathology solely from symptoms, which are often insensitive and nonspecific indicators of disease state (see Beauchaine, Lenzenweger, & Waller, 2008; Meehl, 1995).”

“Taxometric methods were developed as a means of adjudicating between categorical and dimensional models of latent variables by Meehl (1995).”

“Readers interested in substantive aspects of the debate may consult the large set of papers in psychology and psychiatry, including Meehl [ 1 ], Widiger & Clark [2], De Boeck, Wilson & Acton [3] and Markon & Krueger [4].”

“Non-unimodal distributions have been used to investigate subgroups within a construct [57], and bimodality can suggest latent groups [58]; however observed bimodality does not preclude a continuous dimension [59].”

“Third, nuisance correlation (Table 2), which is covariation among indicators that occurs within putative groups of ''narcissists'' and ''non-narcissists,'' was within acceptable limits (i.e., r < .30; Meehl, 1995).”

“Meehl (2001) often speculated that most psychiatric disorders would not have a taxonic structure, yet he pointed out that “I do not hold that if a DSM rubric does not denote an existent taxon in my sense, it is somehow illicit and should be dropped from the nosology” (p.”

“Claims that taxometrics will ‘solve’ the classification problem in psychopathology [13] are clearly overstated.”

“Meehl (1995) noted that although bimodality and marked skewness may be suggestive of latent groups, the presence of bimodality is neither a necessary nor sufficient condition for the existence of latent subgroups.”

“These represent a set of procedures to demonstrate if the latent trait is either dimensional or taxonic (see Meehl, 1995).”

“We drew values from ranges traditionally considered to be adequate for informative taxometric analyses (see Meehl, 1995).”

“related to theoretically, societally, and clinically meaningful outcomes (criteria) that are attributed to dependence (Figures 1 and 2; Meehl, 1995).”

“But as noted above, some leading clinical methodologists contend (e.g., Meehl, 1995; Meehl and Golden, 1982; Waller and Meehl, 1998) that even very strong descriptive similarities between limited and diagnosable depression have no necessary implications for the continuity issue.”

“…(i.e. distributed as a continuous variable, with individuals varying quantitatively from each other) or taxonic (i.e. individuals are differentiated into non-arbitrary groups or categories) (Meehl & Yonce, 1994 ; Meehl, 1995 ; Waller & Meehl, 1998 ; see Ruscio & Ruscio, 2004a for a review).”

“DSM-IV diagnoses (American Psychiatric Association [APA], 1994), for example, might superimpose artificial distinctions on an existing category or continuum ( Meehl, 1995 ).”

“Taxonomic analytic techniques (Meehl, 1995; De Boeck et al., 2005; Ruscio et al., 2006) appear especially well-suited for identifying potential cutoff points.”

“Only two of the main procedures, MAMBAC (acronym from “Mean Above Minus Below A Cut”; Meehl & Yonce, 1994) and MAXCOV (MAXimum COVariance; Meehl, 1973, 1995b; Meehl & Yonce, 1996), have been published in detail (for a summary of them, see Meehl, 1995a ).”

“…(derived within and across taxometric procedures) were numerically consistent, then there would be strong grounds for believing the taxon exists (Meehl, 1995; Waller, personal communication, February 7, 2000; Waller & Meehl, 1998), and it would be a “damn strange coincidence” otherwise (Meehl,…”

“A third method for distinguishing qualitative differences from quantitative differences is the taxometric approach developed by Meehl (1973, 1995, 1999, 2004 ).”

“The taxometric method consists of several diverse analytic procedures that were expressly designed to distinguish taxa from dimensions (e.g., Meehl, 1995, 1999; Meehl & Golden, 1982; Waller & Meehl, 1998).”

“50 as recommended in taxometric analyses (Meehl, 1995).”

“Articles that featured only taxo-metric analyses (Bernstein et al., 2007; Meehl, 1995) — aimed at identifying whether there are two subtypes or no subtypes — were also not included.”

“Given these conflicting findings, the present investigation sought to examine the underlying structure of grief using a group of statistical procedures, collectively referred to as the taxometric method (Meehl 1995), that are specifically designed to distinguish between continuous and categorical structures.”

“First, the sample size ( n = 165) was substantially lower than the minimum of 300 participants recommended by Meehl (1995) for cluster analysis.”

“If several taxometric methods indicated the presence of a taxon, and parameter estimates arrived at in different ways (derived within and across taxometric procedures) were numerically consistent, then there would be strong grounds for believing the taxon existed (Meehl, 1995; Waller, personal communication, February…”

“2A further unfamiliar but potentially useful technique for the diagnosis of pathological grief could be the taxometric approach of Meehl (1995) , who described mathematical procedures that can be used to classify psychiatric patients (for a critical evaluation, see Garb, 1996).”

“The inferential framework implicit throughout much of the literature on the taxometric method (e.g., Meehl, 1995; Meehl & Golden, 1982; Waller & Meehl, 1998) involves the detection of taxonic structure.”

“Likewise, all within-group nuisance correlations were within acceptable margins (r < .30; Beauchaine, 2007, p. 676; Meehl, 1995, p. 273) except for two out of all 18 instances: The within-taxon correlation of the ESIQ and VT in the MAMBAC analysis (.32) and the within-taxon correlations of ESIQ and…”

“The requisite population-based studies, using appropriate structural statistical analyses, eg, finitemixturemodeling (and its derivates)(28,29) or coherent cut kineticmethods(30) havenotbeen carriedout, so it is still possible that a dichotomous latent construct could underlie the skewed distribution of psychosis indi…”

“[19,20] offer a direct way of adjudicating between categorical (‘taxonic’) and continuum (‘dimensional’) models of latent variables.”

“It is generally recommended that taxometric investigations employ indicators with high degrees of validity (i.e., 1.25 SD or greater separation between the proposed taxon and nontaxon groups; Meehl, 1995).”

“In the current study we utilized two taxometric procedures: maximum covariance analysis (MAXCOV; Meehl, 1973; Meehl and Golden, 1982) and mean above minus below a cut (MAMBAC; Meehl, 1995; Meehl and Yonce, 1994).”

“We are aware that cluster analysis is a somewhat controversial technique, and other classification or taxonomic methods are available (Meehl, 1995).”

“One approach to this problem is bootstrapping ( Meehl, 1995 ).”

“The issue, as Skinner and others (Feigl, 1950; Meehl, 1995) have stated, is not whether such constructs are hypothetical, but whether they pay their way in the cost-benefit ratio of constructs to predictions.”

“The mean indicator validity value of 1.28 exceeded the minimal value (σ = 1.25) recommended by Meehl (1995) for proper evaluation of latent structure using the taxometric procedure.”

“…size, moderate within-groups correlations, and two valid indicators of taxon-group membership, x and y, the betweengroups indicator covariances will exceed the withingroups covariances, as specified in the general covari- ance mixture theorem (Meehl, 1995a, p. 271; Meehl & Yonce, 1996, p. 1097).”

“Average indicator validity (Cohen’s d) was 1.80 (σ) using a cutting score of 25 and 1.59 (σ) using a cutting score of 30, both of which exceed the minimally acceptable value of 1.25 (σ) recommended by Meehl (1995).”

“Lacking specification of etiology, we must infer psychopathology solely from symptoms, which are often nonspecific, insensitive markers of disease state (see Beauchaine, Lenzenweger, & Waller, 2008; Meehl, 1995).”

“…somatic symptoms better represent this depressive construct than cognitive and affective symptoms, Beach and Amir conducted taxometric analyses (see Meehl, 1995) of college students’ responses to six somatic items on the Beck Depression Inventory (BDI; Beck, Rush, Shaw, & Emery, 1979) and…”

“Taxometric methods (Meehl, 1995; Schmidt, Kotov, & Joiner, 2004; Waller & Meehl, 1998) are well suited to making this decision.”

“Again, no statistical procedure is self-interpreting (Meehl, 1995, 1999), and taxometrics in this respect is like factor analysis, cluster analysis, multidimensional scaling, or item response theory.”

“A number of studies have used taxometric methods ( Meehl, 1995 ) to address the problem of the latent distribution of psychopathy and antisociality, which contributes to the first two components of the typological model (Edens, Marcus, Lilienfeld, & Poythress, 2006; Guay, Ruscio, Knight, & Hare, 2007; Harris, Rice, &…”

“Taxometric procedures (see Meehl, 1995; Waller & Meehl, 1997) are used to distinguish psychological types (i.e., qualitative differences) from mere variations in a continuum (i.e., just quantitative differences) and, if a construct is typological, to determine a set of indicators for that taxon.”

“Recently, research in this area has moved away from a practical examination of group similarities and differences to a more direct investigation of the underlying structure of eating disorders through taxometric analyses ( Meehl, 1995 ).”

“The difference in observed and latent distributions should not be viewed as a discrepancy, as previous researchers have described the numerous reasons why uni- and bimodal observed score distributions do not imply continuous or categorical latent distributions (Meehl, 1995; Murphy, 1964; Ruscio et al., 2006; Waller &…”

“inverse factor analysis, latent class analysis, mixture analysis, and—a method which I am bold enough to say has definitively solved the problem —my taxometric method, which involves several nonredundant independent procedures (Meehl, 1995).”

“(Beauchaine, 2003; Meehl, 1995).”

“MAXCOV-HITMAX is a taxometric method that examines the maximum covariation between two variables as a function of a third.”

“E-mail: kollman@bu.edu Center for Anxiety and Related Disorders, Boston University, Boston, Massachusetts r 2006 Wiley-Liss, Inc. [e.g., Meehl, 1973, 1995; Meehl and Golden, 1982; Meehl and Yonce, 1994, 1996; J. Ruscio and Ruscio, 2004a; Waller and Meehl, 1998].”

“Dahlstrom (1995), Gangestad and Snyder (1985), and Meehl (1992, 1995) also discussed strong biases against latent taxa.”

“Accordingly, indicator validity parameters (i.e., standardized between-group mean differences, calculated with Cohen's effect size d) estimated by the taxometric programs were also acceptably high (mean indicator validity ϭ 1.75 and 1.36, respectively; see Meehl, 1995a).”

“Taxometric techniques, on the other hand, test the hypothesis of whether the covariation between abuse and dependence criteria is indicative of a latent structure that is dimensional or categorical/taxonic (Meehl, 1995).”