Using taxometric analysis to distinguish a small latent taxon from a latent dimension with positively skewed indicators: the case of involuntary defeat syndrome

Joining the debate on the structure of depression, S. R. H. Bearh and N. Amir (2003) analyzed college students' responses to 6 Beck Depression Inventory (BDI) items with predominantly somatic content and concluded that they identified a small latent taxon corresponding to involuntary defeat syndrome. An exact replication of these analyses yielded virtually identical taxometric results, but parallel analyses of simulated taxonic and dimensional comparison data matching the intercorrelations and skewed distributions of the BDI items showed the results to be more consistent with dimensional than with taxonic latent structure. Analyses in a clinical sample with nonskewed indicators further supported a dimensional interpretation. The authors discuss methodological strategies for conducting and interpreting taxometric analyses under the adverse conditions commonly encountered in psychopathology research, including skewed indicators and small putative taxa.     

Taxometric and factor analytic models of anxiety sensitivity: integrating approaches to latent structural research

This study represents an effort to better understand the latent structure of anxiety sensitivity (AS), as indexed by the 16-item Anxiety Sensitivity Index (ASI; S. Reiss, R. A. Peterson, M. Gursky, & R. J. McNally, 1986), by using taxometric and factor-analytic approaches in an integrative manner. Taxometric analyses indicated that AS has a taxonic latent class structure (i.e., a dichotomous latent class structure) in a large sample of North American adults (N=2,515). As predicted, confirmatory factor analyses indicated that a multidimensional 3-factor model of AS provided a good fit for the AS complement class (normative or low-risk form) but not the AS taxon class (high-risk form). Exploratory factor analytic results suggested that the AS taxon may demonstrate a unique, unidimensional factor solution, though there are alternative indications that it may be characterized by a 2-factor solution. Findings suggest that the latent structural nature of AS can be conceptualized as a taxonic latent class structure composed of 2 types or forms of AS, each of these forms characterized by its own unique latent continuity and dimensional structure.     

Anxiety sensitivity taxonicity across gender among youth

The present investigation comparatively evaluated the latent class structure and parameters of anxiety sensitivity (AS) among female and male youth using the Childhood Anxiety Sensitivity Index. Participants were 4462 adolescents (2189 females) in grades 7-12 (M(age)=15.6 years). Consistent with prediction, taxometric analyses indicated the latent structure of AS was taxonic in both males and females, demonstrating the taxonic latent structure of AS is similarly observed across gender. Also consistent with prediction, the base rate of the AS taxon differed between genders -- higher for females (12%) compared to males (7%). These findings are discussed in terms of their implications for the study of AS and panic vulnerability among youth.     

Taxonicity of anxiety sensitivity: an empirical test among youth

Taxometric coherent cut kinetic analyses were used to test the latent structure of anxiety sensitivity (AS) among 371 youth. Anxiety sensitivity was indexed by the 18-item Childhood Anxiety Sensitivity Index (CASI; Silverman et al., J. Clin. Child Psychol. (1991), 20, 162-168). Two sets of manifest indicators of AS were constructed using the CASI: (1) three item-parcel manifest indicators: disease concerns, unsteady concerns, and mental illness concerns; and (2) nine single-item indicators representing each of these three facets of AS. Results from standard and short-scale MAXCOV procedures, internal consistency tests, analyses of simulated Monte Carlo data, and MAMBAC external consistency tests indicated that the latent structure of anxiety sensitivity among youth was taxonic. Estimated base rate of the observed AS taxon ranged between 13.6 and 16.5%. The present findings are discussed in terms of theoretical implications for the study of AS and vulnerability for anxiety psychopathology.     

What's in a taxon?

Whether taxometrics yields inferential knowledge to something latent is partly but not wholly a semantic question. Although the single variables are manifest indicator scores of individuals, the statistics computed from them via postulates of the formalism are not mere data summaries and will be incorrect or meaningless if the structural conjectures are false. The unidirectional derivability from postulates to data relations supplies the taxonic inferences' surplus meaning that constitutes conventional psychometric meaning of latency (e.g., latent class analysis). Surplus meaning beyond the purely mathematical may be provided by interpretive text attributing unobserved attributes or causal origin to taxon members.     

Taxometric and factor analytic models of anxiety sensitivity among youth: exploring the latent structure of anxiety psychopathology vulnerability

This study represents an effort to better understand the latent structure of anxiety sensitivity (AS), a well-established affect-sensitivity individual difference factor, among youth by employing taxometric and factor analytic approaches in an integrative manner. Taxometric analyses indicated that AS, as indexed by the Child Anxiety Sensitivity Index (CASI; Silverman, Flesig, Rabian, & Peterson, 1991), demonstrates taxonic latent class structure in a large sample of youth from North America (N=4,462; M(age)=15.6 years; SD=1.3). Subsequent confirmatory factor analyses indicated that the latent continuous, multidimensional, 4-factor model of AS among youth (Silverman, Goedhart, Barrett, & Turner, 2003) provided good fit for the CASI data among the complement class ("normative form" of AS), but not among the taxon class ("high-risk form" of AS). EFAs supported the prediction that the AS taxon demonstrates a unique, heretofore unexplored latent continuous, unidimensional factor structure among youth. Findings are discussed in relation to refining our understanding of the latent structure of AS and the clinical implications that arise from it.     

Is schizotypy taxonic? Response to

Beauchaine, Lenzenweger, and Waller (2008) criticize our taxometric study of schizotypy (Rawlings, Williams, Haslam, & Claridge, in press) on a variety of methodological and philosophical grounds. We argue that their critique selectively applies more stringent standards to our work than to studies supporting their view that schizotypy is taxonic (i.e., categorical). Many of their criticisms apply at least equally to existing studies that offer support for a schizotypy taxon, and these studies are vulnerable to biases favouring taxonic conclusions that were controlled for in our study. Contrary to their criticisms, we did not claim to have disconfirmed previous taxonic findings about schizotypy, and our findings positively support dimensional models of schizotypy rather than merely being null results. Similarly, our findings are not artefacts of the sampling or measurement decisions that they question. Even well-replicated taxometric findings are not immune to empirical challenge, and evaluation of such challenges must be even-handed.     

Confirming the latent structure and base rate of schizotypy: a taxometric analysis.

Meehl's (1962, 1990) model of schizotypy and the development of schizophrenia implies that the structure of liability for schizophrenia is dichotomous and that a "schizogene" determines membership in a latent class, or taxon (Meehl & Golden, 1982). The authors sought to determine the latent structure and base rate of schizotypy. They applied Meehl's (1973; Meehl & Golden, 1982) MAXCOV-HITMAX taxometric analytic procedures to a subset of items from the Perceptual Aberration Scale (PAS; Chapman, Chapman, & Raulin, 1978), a prominent psychometric index of schizotypy, derived from a randomly ascertained nonclinical university sample (N = 1,093). The results, in accordance with Meehl's conjectures, strongly suggest that schizotypy, as assessed by the PAS, is taxonic at the latent level with a general population taxon base rate of approximately .10.     

Malingering as a categorical or dimensional construct: the latent structure of feigned psychopathology as measured by the SIRS and MMPI-2

The 6 nonoverlapping primary scales of the Structured Interview of Reported Symptoms (SIRS) were subjected to taxometric analysis in a group of 1,211 criminal and civil examinees in order to investigate the latent structure of feigned psychopathology. Both taxometric procedures used in this study, mean above minus below a cut (MAMBAC) and maximum covariance (MAXCOV), produced dimensional results. A subgroup of participants (n = 711) with valid Minnesota Multiphasic Personality Inventory-2 (MMPI-2) protocols were included in a second round of analyses in which the 6 nonoverlapping primary scales of the SIRS and the Infrequency (F), Infrequency-Psychopathology (Fp), and Dissimulation (Ds) scales of the MMPI-2 served as indicators. Again, the results were more consistent with dimensional latent structure than with taxonic latent structure. On the basis of these findings, it is concluded that feigned psychopathology forms a dimension (levels of fabrication or exaggeration) rather than a taxon (malingering-honest dichotomy) and that malingering is a quantitative distinction rather than a qualitative one. The theoretical and clinical practice implications of these findings are discussed.     

The taxon concept: is it taxonic?

The question of whether the concept of a "taxon" (a nonarbitrary latent category) is itself categorical, or is a matter of degree, has lain dormant within taxometrics. I analyze the problem conceptually. Part of the meaning of "taxon," I hold, goes beyond the manifest statistical properties of admixed probability distributions; any of certain forms of causal nexus leading to admixed distributions are involved as well. I defend the thesis that the threshold question, "Is there a taxon?" has a yes-or-no answer, establishing that "taxonicity" is categorical (taxonic), but also that as some taxa are much more readily distinguished from their complement classes than are others, the taxon question is also quantitative. It is on this basis that Meehl and others held the view that taxonicity is a matter of degree; however, they were wrong to hold that it is only a matter of degree.     

Clarifying boundaries of binge eating disorder and psychiatric comorbidity: a latent structure analysis

Binge eating disorder (BED) presents with substantial psychiatric comorbidity. This latent structure analysis sought to delineate boundaries of BED given its comorbidity with affective and anxiety disorders. A population-based sample of 151 women with BED, 102 women with affective or anxiety disorders, and 259 women without psychiatric disorders was assessed with clinical interviews and self-report-questionnaires. Taxometric analyses were conducted using DSM-IV criteria of BED and of affective and anxiety disorders. The results showed a taxonic structure of BED and of affective and anxiety disorders. Both taxa co-occurred at an above-chance level, but also presented independently with twice-as-large probabilities. Within the BED taxon, diagnostic co-occurrence indicated greater general psychopathology, lower social adaptation, and greater premorbid exposure to parental mood and substance disorder, but not greater eating disorder psychopathology. Eating disorder psychopathology discriminated individuals in the BED taxon from individuals in the affective and anxiety disorders taxon. Diagnostic criteria of BED were more indicative of the BED taxon than were criteria of affective and anxiety disorders. The results show that at the latent level, BED was co-occurring with, yet distinct from, affective and anxiety disorders and was not characterized by an underlying affective or anxiety disorder.     

Taxometric analysis supports a dimensional latent structure for schizotypy

The existence of a discrete class of people vulnerable to schizophrenia spectrum disorders is the most replicated finding of taxometric research. Evidence for such a “taxon” has been obtained with diverse measures of schizotypy in clinical, high-risk, and normal samples. However, recent demonstrations that skewed indicators of a latent dimension can yield a spuriously taxonic pattern of results may call some of these findings into question. Normal adults (N = 1073) completed measures of positive (perceptual aberration, magical ideation) and negative (physical and social anhedonia) components of schizotypy. Taxometric curves resembled those obtained previously, but when a simulation procedure took skew into account, dimensional models of schizotypy received stronger support than taxonic models for most schizotypy components, with findings for magical thinking inconclusive. A re-evaluation of previous taxonic conclusions regarding the latent structure of schizotypy is indicated.     

Depression proneness in treatment-seeking smokers: a taxometric analysis

Using taxometric procedures, we examined latent distribution of depression proneness and the construct validity of the Depression Proneness Inventory (DPI) within a group of 439 non-depressed smokers participating in a smoking cessation trial. Three taxometric procedures MAMBAC, MAXEIG, and L-MODE, supported the presence of a distinct subgroup of depression prone smokers. A set of indicators including cognitive vulnerabilities, self-reported tendencies to feel inadequate and experience depressive symptoms, as well as recent experiences of depressive symptoms prior to anticipated cessation treatment behaved taxonically suggesting a shared relationship with an underlying taxonic causal factor. The DPI was found to be an efficient index of taxon membership and a strong predictor of depression history. The DPI identifies a subgroup of smokers seeking cessation treatment that carry affective risk factors known to impede successful smoking cessation and might benefit from interventions targeting depression and negative mood.     

A Person‐Centered Examination of Adolescent Religiosity Using Latent Class Analysis

Empirical studies of religion's role in society, especially those focused on individuals and analyzing survey data, conceptualize and measure religiosity as ranging from low to high on a single measure or a summary index of multiple measures. Other concepts, such as “lived religion,” “believing without belonging,” or “fuzzy fidelity” emphasize what scholars have noted for decades: humans are rarely consistently low, medium, or high across dimensions of religiosity including institutional involvement, private practice, salience, or belief. A method with great promise for identifying population patterns in how individuals combine types and levels of belief, practice, and personal religious salience is latent class analysis. In this article, we use data from the first wave of the National Study of Youth and Religion's telephone survey to discuss how to select indicators of religiosity in an informed manner, as well as the implications of the number and types of indicators used for model fit. We identify five latent classes of religiosity among adolescents in the United States and their sociodemographic correlates. Our findings highlight the value of a person‐centered approach to understanding how religion is lived by American adolescents.     

A taxometric analysis of psychopathic personality

Although a common assumption throughout much of the professional and popular literature is that psychopaths are qualitatively different from others, very few studies have examined the latent structure of psychopathy. Whether psychopathy is a discrete category or a continuous dimension may have implications for research on the assessment, etiology, and treatment of this disorder. This study examined the latent structure of psychopathy in a sample of 309 jail and prison inmates. Three taxometric procedures were used to analyze indicators drawn from the Psychopathic Personality Inventory (S. O. Lilienfeld & B. P. Andrews, 1996), a self-report instrument. Consistent with prior studies that used other measures of psychopathy, none of the analyses was consistent with a taxonic solution, suggesting that psychopathic personality may be best understood as existing on a continuum.     

Deeper into the schizotypy taxon: on the robust nature of maximum covariance analysis

Prior research has suggested that the latent structure of the schizotypy construct (P. E. Meehl, 1990) may be qualitative in nature and have a low base rate (L. Korfine & M. F. Lenzenweger, 1995; M. F. Lenzenweger & L. Korfine, 1992). These studies relied on the application of maximum covariance analysis (MAXCOV) to 8 true-false format items from a schizotypy measure. The current study sought to examine the robustness of those prior findings through MAXCOV analysis of fully quantitative measures of schizotypy. Measures of perceptual aberration, magical ideation, and referential thinking were analyzed using MAXCOV in a sample of 429 persons. The results of these analyses strongly support a latent taxonic structure for schizotypy and a low base rate for the schizotypy taxon. Furthermore, the members of the putative taxon reveal an increased level of deviance on a psychometric measure known to be associated with schizophrenia liability. The possibility that the dichotomous item format of those items analyzed previously with MAXCOV lead to spurious pseudotaxonicity is greatly diminished in light of these results.     

The psychometric detection of schizotypy: do putative schizotypy indicators identify the same latent class?

The authors examined whether three indicators of Schizotypy, the Revised Social Anhedonia Scale (RSAS), Magical Ideation Scale (MIS), and Perceptual Aberration Scale (PAS), identify a common latent class or taxon as conceptualized by P. E. Meehl (1962, 1990). The separate and joint latent structures of these scales were evaluated using taxometric methods in two large, independent samples. Replicating prior findings, the RSAS and PAS each identified latent taxa with base rates approximating.10. Results for the taxonicity of the MIS were less consistent. Analyses of joint latent structure indicated that the RSAS-identified taxon was essentially independent of constructs measured by the PAS or MIS. Measures commonly thought to tap the same latent class, conjectured to be schizotypy, do not share this property.     

Psychopathic, not psychopath: taxometric evidence for the dimensional structure of psychopathy

Although psychopathy is frequently regarded as qualitatively distinct from other conditions, relatively little research has examined whether psychopaths represent a distinct class of individuals. Using a sample of 876 prison inmates and court-ordered substance abuse patients who were administered the Psychopathy Checklist-Revised (R. D. Hare, 2003), the authors examined the latent structure of psychopathy using several taxometric procedures developed by Meehl and colleagues (P. E. Meehl & L. J. Yonce, 1994; N. G. Waller & P. E. Meehl, 1998). The results across these procedures offer no compelling support for the contention that psychopathy is a taxonic construct and contradict previous reports that psychopathy is underpinned by a latent taxon. The authors discuss the theoretical, public policy, and practice-level implications of these findings.     

Exploring the latent structure of the Perceptual Aberration, Magical Ideation, and Physical Anhedonia Scales in a German sample.

The schizotypy model proposed by Meehl (1990) assumes a discontinuous distribution of schizophrenia liability. The "schizogene" is thought to determine if one is at risk for psychosis (i.e., whether one is a member of the taxon or its complement, which are considered to be the two latent classes). Using a German non-student sample (n = 809) we wanted to (1) replicate the results of prior research pertaining to the latent structure and base rate of schizotypy assessed by the Perceptual Aberration Scale (PER; Chapman, Chapman, & Raulin, 1978), and (2) investigate whether the same holds true for two other prominent psychometric indices, the Magical Ideation Scale (MI; Eckblad & Chapman, 1983) and the Physical Anhedonia Scale (PhA; Chapman et al., 1976), if one uses the same kind of analysis--the MAXCOV-HITMAX analysis based on subsets of items (Meehl, 1973). Pertaining to PER and PhA, our results are in accordance with prior research showing a latent class structure and a base rate of about 12% for schizotypy. However, for MI, there was no evidence of a taxonic structure. Possible reasons for MI's negative results are discussed as well as the role of the concept "anhedonia."     

Type or dimension? A taxometric investigation of flashbulb memories

Flashbulb memories (FBMs) have been defined as vivid and detailed memory of a reception context under which one first heard of a public and unexpected emotional event. One of the issues still open for research on FBMs is to understand whether this latent construct has to be conceptualised as a continuum with other autobiographical memories, or whether it represents a special cluster of memories. This theoretical distinction has some implications for the measurement of the phenomenon, that could be assessed by a dimensional or categorical (taxonic) model. The current study attempted to provide an empirical answer to the problem of FBM measurement, by adopting a taxometric analysis. The main strength of these analyses is to treat taxonic and dimensional models as two competing hypotheses and to evaluate the relative support for each of them. Taxometric analyses were applied to FBM data for the Pope's death, and results supported the taxonic structure of FBMs.