Taxometric Procedures Research Articles

Is antisocial personality disorder continuous or categorical? A taxometric analysis

Although the DSM-IV-TR is organized into discrete disorders, the question of whether a given disorder possesses a dimensional or a categorical latent structure is an empirical one that can be examined using taxometric methods. The objective of this study was to ascertain the latent structure of antisocial personality disorder (ASPD). Participants were 1146 male offenders incarcerated in state prisons (n=569), or court-ordered to residential drug treatment (n=577). Participants were interviewed using the Structured Clinical Interview for DSM-IV Axis II Personality Disorders (SCID-II) to assess ASPD symptoms; they also completed the Personality Diagnostic Questionnaire-4 (PDQ-4) ASPD scale. Taxometric analyses were performed to examine whether ASPD is underpinned by a discrete category or a dimensional construct. Multiple taxometric procedures using two different sets of indicators provided no evidence that ASPD has a taxonic latent structure. Instead, the results were far more consistent with the proposition that ASPD exists on a continuum, regardless of whether it is assessed using a structured interview or a self-report measure. Evidence that ASPD is dimensional suggests that it is best studied using continuous measures and that dichotomizing individuals into ASPD versus non-ASPD groups will typically result in decreased statistical power. The findings are also consistent with a multifactorial etiology for ASPD and with recent attempts to conceptualize ASPD within the framework of extant dimensional models of personality.

A Taxometric Study of the Center for Epidemiological Studies Depression Scale

The authors assessed the latent structure of depressive symptoms as measured by the Center for Epidemiological Studies Depression Scale (CES-D; L. S. Radloff, 1977). By using taxometric procedures, the authors conducted analyses of CES-D data obtained from a large college student population. These procedures incorporated strategies for interpreting analyses of skewed indicators and small putative taxa. The authors hypothesized that CES-D total scores would be represented as a dimension, with a taxonic distribution of a factor incorporating somatic symptoms. Results indicated that all CES-D factors, including the factor composed of somatic complaints, were dimensional. Administration of the Diagnostic Interview Schedule-IV (L. N. Robins, L. Marcus, & W. Reich, 1996) to one quarter of the participants indicated that the CES-D was effective in identifying cases of current or recent clinical depression. Evidence of the dimensionality of CES-D indicators in a student population is consistent with a continuity view of depressive symptoms.

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.

Taxometric analyses in psychological research and in classification of mental disorders

The issue of whether manifest psychological variables comprise a latent taxonic or dimensional structure is essential to the contemporary psychology and psychiatry. Fortunately, this issue can be adequately addressed by using several taxometric procedures, all developed over the last few decades. This paper describes five of the most commonly used analyses, as follows: Mean-Above-Mean-Below-A-Cut (MAMBAC), Maximum Covariance (MAXCOV), Maximum Eigen-Value, (MAXEIG), Latent Mode (L-Mode), and Maximum Slope (MAXSLOPE). In addition, this paper briefly outlines Paul Meehl?s diathesis-stress model of schizophrenia and highlights the practical importance of taxometric procedures in both contemporary psychology and in the classification of psychiatric disorders.

Evaluating the latent structure of the MMPI-2 F(p) scale in a forensic sample: A taxometric analysis.

P. A. Arbisi and Y. S. Ben-Porath (1995) originally proposed that the Infrequency Psychopathology scale, F(p), be used as the final step in an algorithm to determine the validity of a Minnesota Multiphasic Personality Inventory-2 (MMPI-2) protocol. The current study used taxometric procedures to determine the latent structure of F(p) among examinees with profiles that would necessitate the interpretation of F(p) when using Arbisi and Ben-Porath's proposed algorithm. Participants included a subsample of 289 consecutively referred pretrial forensic examinees adjudicated incompetent to stand trial with high Infrequency (F) scale scores, thereby providing a sample that would be expected to have a high base rate of persons with bona fide psychopathology and persons with incentive to overreport psychopathology. Using MAMBAC and MAXEIG, F(p) produced a taxonic latent structure within the subgroup of examinees who obtained raw scores on F of greater than 17. These results support Arbisi and Ben-Porath's original proposal to use F(p) to identify a distinct subgroup of overreported MMPI-2 protocols within forensic psychiatric examinees with high elevations on F. Implications and suggestions for future research are provided.

Self-Reported Depression Is Taxonic

Using the Sample-specific simulation method proposed by J. Ruscio, A. M. Ruscio, and T. M. Keane (2004 ), the S. R. H. Beach and N. Amir (2003) data are re-analyzed. The results for the MAXEIG and MAMBAC procedures are compared across simulated dimensional, simulated taxonic, and original distributions. The comparison indicates that depression is taxonic in the S. R. H. Beach and N. Amir (2003) sample but has a lower base (.06) than previously reported. This result indicates the need to use a relatively high cut point on total Beck Depression Inventory (i.e., BDI>21; A. T. Beck, 1978) when creating groups using the BDI. That is, the data support the presence of a discontinuity between “depressed” and “nondepressed” undergraduates at a relatively high level of depressive symptomatology. At the same time, it is noted that researchers should remain cautious about the interpretation of taxometric procedures used with low base rate taxa until they have been further investigated using Monte Carlo simulations.

A Taxometric Investigation of Unipolar Depression in the National Comorbidity Survey.

Ongoing debate has questioned whether unipolar depression is a dimensional or categorical phenomenon. Although past studies using taxometric methods have supported a dimensional interpretation, each has suffered from methodological limitations. The present study was designed to overcome these limitations through reanalysis of the National Comorbidity Survey. Two indicator sets were constructed from the depression-relevant questions of the Composite International Diagnostic Interview. Participants who endorsed the lifetime occurrence of significant depressed mood or anhedonia (n=4,577) were submitted to 2 nonredundant taxometric procedures (maximum eigenvalue and means above minus below a cut), additional consistency tests, and recently developed simulation techniques. All results converged on a dimensional solution. The implications of these findings on assessment, treatment, and research design are discussed.

A taxometric investigation of dissociation in Vietnam veterans

There is long-standing debate about whether elevated dissociative symptoms are common in posttraumatic stress disorder (PTSD) or whether there is a distinct subtype of cases with elevated dissociation. The current investigation examined the latent structure of dissociative symptoms in a sample of 316 male, trauma-exposed Vietnam veterans, 76 of whom were diagnosed with current PTSD. Three taxometric procedures (MAMBAC, MAXEIG, and MAXCOV) were performed on three indicator sets drawn from the Dissociative Experiences Scale. Taxometric analyses consistently revealed a taxon (subtype) of highly dissociative individuals. The taxon members had significantly more severe posttraumatic symptoms and were more often diagnosed with current PTSD than were non-taxon members. Among participants with a current PTSD diagnoses, only 32% belonged to the dissociative taxon, suggesting that there is a subtype of severe PTSD with elevated dissociation.

The Latent Structure of Psychopathy in Youth: A Taxometric Investigation

Using taxometric procedures, the latent structure of psychopathy was investigated in two studies of children and adolescents. Prior studies have identified a taxon (i.e., a natural category) associated with antisocial behavior in adults as well as children and adolescents. However, features of this taxon suggest that it is not psychopathy but rather a broader class consistent with the construct of life course persistent antisocial behavior. Because the only prior study of youth used a non-clinical sample, the base rate of psychopathy may have been too low to reveal a psychopathy taxon, especially against the background of a broader and more prevalent antisocial behavior taxon. Therefore, this investigation sought to increase the likelihood of finding a psychopathy taxon (should one exist) by increasing its expected base rate through inclusion of clinical cases in the samples studied. Results produced evidence for both a broad antisocial behavior problem taxon consistent with past research and a much lower base rate taxon consistent with prevalence expectations for psychopathy. These findings support the existence of latent taxa for both psychopathy and a broader class of antisocial behavior problems. Further taxometric research appears to be warranted, which should use a broader array of indicators, with greater specificity to psychopathy.

Examining the latent structure of negative symptoms: Is there a distinct subtype of negative symptom schizophrenia?

Negative symptoms have emerged as a replicable factor of symptomatology within schizophrenia. Although rating scales provide assessments along dimensions of severity, categorization into a negative symptom subtype is typically conducted. A categorical view of negative symptoms is best reflected in the proposal that enduring, primary negative symptoms, or deficit symptoms, reflect a distinct subtype of schizophrenia [Carpenter, W.T., Heinrichs, D.W., Wagman, A.M.I., 1988. Deficit and nondeficit forms of schizophrenia: The concept. Am. J. Psychiatry 145, 578–583.]. Despite an accumulation of findings that support a categorical conceptualization, the data are also consistent with a dimensional-only model where negative symptom subtypologies simply reflect an extreme on a continuum of severity. Using taxometric statistical methods [Waller, N.G., Meehl, P.E., 1998. Multivariate Taxometric Procedures: Distinguishing Types From Continua. Sage, Newbury Park, CA.], the present study examined whether a taxonic, or latent class, model best describes negative symptoms in a sample of 238 schizophrenia patients. In order to obtain more stable estimates of symptoms, ratings on the Scale for the Assessment of Negative Symptoms [Andreasen, N.C., 1982. Negative symptoms in schizophrenia: Definition and reliability. Arch. Gen. Psychiatry 39, 784–788.] were averaged across two assessments over a 6-month period. Two taxometric methods, maximum covariance analysis (MAXCOV) and mean above minus below a cut (MAMBAC) identified a latent class or taxon with a base rate of approximately 28–36%. Members of the negative symptom taxon differed from the nontaxon class in that taxon members were more likely to be male and demonstrated poorer social functioning. Taxon and nontaxon schizophrenia patients did not differ in psychotic or affective symptoms. The findings converge to provide support for a categorical view of negative symptoms. Further research is required to replicate the present taxonic findings and to examine characteristics (including possible etiological factors) associated with this negative symptom taxon.

Is Depression Best Viewed as a Continuum or Discrete Category? A Taxometric Analysis of Childhood and Adolescent Depression in a Population-Based Sample.

The authors examined the latent structure of depression in a population-based sample of children and adolescents. Youth's self-reports and parents' reports of the youth's Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; American Psychiatric Association, 1994) major depressive symptoms were assessed via a structured clinical interview. The authors used Meehl's (1995) taxometric procedures to discern whether youth depression is dimensional or categorical. Taxometric analyses that explicitly took into account the skewness of depressive symptoms suggested that depression is a dimensional, not categorical, construct. The dimensional structure of depression was obtained for all of the DSM-IV major depressive symptoms as well as for different domains of depression (emotional distress symptoms and vegetative, involuntary defeat symptoms), youth and parent reports, and different subsamples (i.e., boys vs. girls and younger vs. older youth).

Testing the latent structure of posttraumatic stress disorder: A taxometric study of combat veterans

Since the diagnosis of posttraumatic stress disorder (PTSD) first appeared in the psychiatric nomenclature in 1980, considerable debate has revolved around the nature of the condition. Specifically, is PTSD best conceptualized as one end of a continuum of human response to traumatic stress or does it represent a discontinuous latent category? Two taxometric procedures were used to investigate this issue in a random community sample of 692 Australian combat veterans, using structured interview and self-report instruments to assess PTSD symptomatology. Findings favored a dimensional model of PTSD, consistent with previous taxometric work on treatment-seeking samples (A. Ruscio, Ruscio, & Keane, 2002). Implications are drawn for the conceptualization, etiology, and assessment of PTSD.

Latent structure of depression in a community sample: a taxometric analysis

The latent structure of depression was examined using taxometric analysis, a family of statistical procedures designed specifically to test whether a given construct is best conceptualized as a distinct category or a continuous dimension. Data were derived from the Australian National Survey of Mental Health and Well-Being, a large epidemiological survey that measured the prevalence of the major DSM-IV and ICD-10 mental disorders. Two taxometric procedures, maximum covariance (MAXCOV) and mean above minus below a cut (MAMBAC), were carried out on a sample of 1933 community volunteers. Simulated categorical and dimensional datasets aided in the interpretation of the research data. The results of the taxometric analyses in the subsample who endorsed at least one symptom of depression were consistent with a dimensional latent structure of depression. The findings of the current study suggest that depression, as measured in this subsample, is best conceptualized, measured and classified as a continuously distributed syndrome rather than as a discrete diagnostic entity. Incorporation of dimensional measurement into psychiatric classification systems remains a challenge for the future.

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.

The Maxslope Taxometric Procedure: Mathematical Derivation, Parameter Estimation, Consistency Tests

This article first explains concepts in taxometrics, including the meaning of "taxon" in relation to taxometric procedures. It then mathematically develops the MAXSLOPE procedure of Grove and Meehl which relies on nonlinear regression of one taxometric indicator variable on another. Sufficient conditions for MAXSLOPE's validity are set forth. The relationship between the point of maximum regression slope (MAXSLOPE point) and the HITMAX cut, i.e., the point on a variable which, if used as a diagnostic cut-off score, yields maximum classification accuracy, is analyzed. A sufficient condition is given for the MAXSLOPE point to equal the HITMAX cut; however, most distributions have different MAXSLOPE and HITMAX points. Equations and an algorithm are spelled out for making a graphical test for the existence of a taxon, estimating taxometric parameters, and conducting consistency tests; the latter serve as stringent checks on the validity of a taxonic conjecture. The plausibility of assumptions made, in deriving MAXSLOPE equations, is discussed, and the qualitative effects of violations of these assumptions are explained.

A Nontechnical Introduction to the Taxometric Method

Although social and behavioral scientists often presume that individual differences underlying measured variables consist of differences in degree rather than differences in kind, the distinction between taxonic (categorical) and dimensional (continuous) latent structure poses an empirical question with important implications for basic and applied science. In this article, we present a nontechnical introduction to the taxometric method for assessing latent structure. We outline unique features of the general approach and then describe and illustrate specific taxometric procedures, emphasizing the conceptual logic of each analytic technique, factors that can influence results and their interpretation, and decisions that must be made to implement each procedure most appropriately and powerfully. We present a number of refinements and extensions to taxometric methodology including a useful interpretive aid based on the parallel analysis of simulated taxonic and dimensional comparison data. We focus on practi...

Taxometric analyses of specific language impairment in 3- and 4-year-old children.

Specific language impairment (SLI), like many diagnostic labels for complex behavioral conditions, is often assumed to define a category of children who differ not only in degree but also in kind from children developing language normally. Although this assumption has important implications for theoretical models and clinical approaches, its validity has not been tested. In this study, distributions of language scores from children at ages 3 (N = 620) and 4 (N = 623) years were analyzed using a taxometric procedure known as "mean above minus below a cut" (MAMBAC; P. E. Meehl and L. J. Yonce, 1994). Language scores were distributed dimensionally at both ages, failing to support the hypothesis of a qualitatively distinct group corresponding to children with SLI.

A conceptual and methodological checklist for conducting a taxometric investigation

The taxometric method is an increasingly popular statistical approach that tests whether the structure of a latent construct is categorical or continuous. This article presents the key conceptual and methodological issues that should be addressed in an informative taxometric investigation. We aim to help potential users of taxometrics determine: (a) when a taxometric analysis is scientifically justified, (b) whether their data are suitable for taxometric analysis, (c) whether they have properly implemented a sufficient variety of taxometric procedures, (d) whether they have appropriately presented and interpreted the obtained results, and (e) whether they have adequately articulated the implications of their structural solution. Annotated program code and empirical examples are provided to illustrate how taxometric analysis is applied in practice.

A taxometric study of borderline personality disorder.

Taxometric methodology was used to determine whether borderline personality disorder (BPD) represents a taxon that is categorically distinct from normal personality or whether it falls on a dimensional continuum with normality. Two taxometric procedures were used with a sample of 1,389 outpatients assessed for BPD symptoms by semistructured interview. The procedures indicated that BPD does not represent a latent category. Implications are drawn for the conceptualization and etiology of BPD, and for the categorical versus dimensional status of personality disorders in general.

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.