Logistic regression

Logistic regression has probably been underutilized in clinical investigations of personality because of its relatively recent development (dictated by the need for computer programs to obtain maximum likelihood estimates), and the fact that use has been largely confined to the fields of biostatistics, epidemiology, and economics Its use should be given serious consideration when the outcome of interest is dichotomous (or polychotomous) in nature and the predictors of interest may be categorical or continuous. The logit transformation is quite tractable mathematically, and it embodies the notion of threshold, which may have relevance for many of the variables that are of interest to investigators in the field of personality. Furthermore, investigators with experience in multiple linear regression or contingency table analysis should have little trouble in transitioning to logistic regression. Logistic regression programs are readily available in the major statistical packages, all of which provide fairly standard output.     

Defining stuttering for research purposes

This is a response to a Letter to the Editor entitled “Stuttering prevalence, incidence and recovery rates depend on how we define it: Comment on Yairi & Ambrose’ article Epidemiology of Stuttering: 21st Century advances” by Paul Brocklehurst (2013). The criticism was directed specifically toward Yairi and Ambrose’ conclusions, based on review of recent studies, regarding the incidence and prevalence of stuttering. In this response, Brocklehurst's arguments and suggestions of criteria for incidence research are discussed and negated.     

Effects of subgrouping in stuttering research

The most frequently utilized research design in stuttering research compares stutterers to nonstutterers, with the assumption that stutterers represent a homogeneous group. The present study examines the effects of subgrouping stuttering subjects. Sample populations were randomly selected from a pool of stuttering children, successively increasing the stringency of selection criteria for group membership. The groups were contrasted across five dependent variables. The results indicated that the performance differences between the groups increased as the selection criteria became more stringent. The findings were interpreted as supporting the need to more closely examine the individual differences of stutterers, deviating from the traditional research paradigm.     

Phonation in stuttering: A review of current research

Current research including studies which implicate the phonatory mechanism in stuttering as well as physiological studies offering direct evidence of abnormal laryngeal activity in stuttering are reviewed. It is concluded that while present research does not support claims for laryngeal causation of stuttering, the evidence is strong that abnormal laryngeal behaviors are an important aspect of the disrupted peripheral speech physiology that characterizes stuttering. Since this is true, it follows that abnormal laryngeal behavior deserves consideration in the diagnosis and management of stuttering.     

Tokens for stuttering

Four young stutterers were observed during 10 weekly sessions. Each session was divided into pretreatment, treatment, and posttreatment segments. Redeemable tokens were administered contingent upon stuttering behaviors in the treatment segment of the Experimental condition. In a Parallel Control condition, no tokens were administered during the entire session. The differences between the pretreatment and treatment segments were compared for the two conditions. Three subjects had dramatically fewer stuttering behaviors when tokens were being administered, while the fourth had more stuttering under the same condition. The subject whose stuttering increased had a history of therapy in which voluntary, “faked” stuttering had been called for, and the behaviors that increased were judged to be of this type. The decreases were interpreted as suggesting that the contingent tokens acted to countercondition the aversiveness of the stuttering experience, which reduced the anticipation of stuttering and hence the stuttering itself. The increase was felt to be simple reinforcement. The counterconditioning interpretation was borne out in two clinical applications in which money was presented contingent on stuttering behaviors judged to be aversive to the stutterer, and in which dramatically sudden, but long-lasting, improvement was seen.     

The effect of punishment on a factor I stuttering behavior

On each of five days the subject of this experiment read aloud different material during an 18-min A₁ (base rate), B (experimental), and A₂ (extinction) period. No stimulation was delivered during the first three days. On the fourth day, the nonsense word “norg” was presented noncontingently during the experimental period. There was no statistically significant difference between the A₁ and B periods on any of these four days. On day five, “wrong” was made contingent on Factor I prolongations during the experimental period. As a result, there was a statistically significant increase in their frequency. When the response consequence was removed in the A₂ priod, there was a reliable reduction in prolongations and the frequency closely approximated that found in the A₁ period. These data suggest that response-contingent negative stimulation is contraindicated as a clinical tactic for use with Factor I prolongations. It not only failed to suppress them, it increased their frequency.     

An exploratory factor analysis of action responses to stuttering anticipation

PurposeWe previously introduced theStuttering Anticipation Scale (SAS; Jackson, E. S., Gerlach, H., Rodgers, N. H., & Zebrowski, P. M. (2018). My Client Knows That He’s About to Stutter: How Can We Address Stuttering Anticipation during Therapy with Young People Who Stutter? Seminars in Speech and Language, 39, 356–370) – a non-standardized self-report measure for children, teens, and adults who stutter (CWS, TWS, AWS) that quantifies how often they engage in 25 commonly reported action responses to anticipation. The purpose of this study was to leverage the SAS to explore the factor structure of action responses to stuttering anticipation.MethodsA total of 121 people who stutter completed the SAS online (27 CWS, 40 TWS, 54 AWS). We used exploratory factor analysis (EFA) to determine the underlying latent variables within the 25 SAS items that characterize how people who stutter respond to anticipation.ResultsA three-factor model was most appropriate for the data with regard to factor loadings and other model fit indices. The three factors were named: avoidance (17 items), physical change (4 items), and approach (4 items).ConclusionUnderstanding these three types of action responses to anticipation can help guide clinical decision-making by providing a novel framework for clinicians and their clients who stutter to discuss how the client tends to respond to anticipation, and explore ways to facilitate productive responses to anticipation.     

A critical review of a recent decade of stuttering research

The purpose of the present investigation was to catalogue and evaluate portions of the literature on stuttering from 1967 to 1977. Of particular interest was the identification of the research literature. Of 287 articles located and evaluated, 181 were research reports. These reports were categorized according to topics, subject selection, subjects' characteristics, type of research designs and use of randomization, reliability, and statistical methods. Unhappily, many of the faults identified in reviews ten to twenty years earlier tended to persist, and many of the deficiencies recently cited by authorities in the field were found to characterize this literature.     

Working memory involvement in stuttering: exploring the evidence and research implications

Several studies of utterance planning and attention processes in stuttering have raised the prospect of working memory involvement in the disorder. In this paper, potential connections between stuttering and two elements of Baddeley's [Baddeley, A. D. (2003). Working memory: Looking back and looking forward. Neuroscience, 4, 829-839] working memory model, phonological memory and central executive, are posited. Empirical evidence is drawn from studies on phonological memory and dual-task performance among children and adults who stutter to examine support for the posited connections. Implications for research to examine working memory as one of the psycholinguistic bases of stuttering are presented. EDUCATIONAL OBJECTIVES: The reader will learn about and be able to: (1) appraise potential relationships between working memory and stuttering; (2) evaluate empirical evidence that suggests the possibility of working memory involvement in stuttering; and (3) identify research directions to explore the role of working memory in stuttering.     

Parent perceptions of an integrated stuttering treatment and behavioral self-regulation program for early developmental stuttering

PurposeRecent research has identified approximately half of children who stutter present with self-regulation challenges. These manifest in elevated inattentive and/or impulsive behaviours, aligned with attention deficit hyperactivity disorder (ADHD) symptoms. These symptoms have been found to influence the child’s responsiveness to their stuttering treatment, and may exacerbate the psychosocial consequences of stuttering for them and their families. Early stuttering intervention identifies parents as key agents of change in the management of their children’s stuttering. This study sought feedback from parents regarding their experiences with an integrated stuttering treatment and behavioral self-regulation program for early developmental stuttering, addressing the child’s self-regulation challenges.MethodEight parents of children who stutter who had co-occurring self-regulation challenges completed the integrated program. This incorporated the Triple P--Positive Parenting Program adapted for the developmental stuttering population, and the Curtin University Stuttering Program (CUSP). Semi-structured qualitative interviews were conducted to capture parents’ reflections on, and experiences with, the integrated program.ResultsThematic analysis identified several major themes regarding the parents’ experiences with the integrated program: emotional impact on parents, child self-regulation, link between stuttering and behaviour, parent self-regulation, impact on family dynamics, and overall positive perceptions of the integrated program. All of the parents indicated they would recommend the program to future parents of children who stutter.ConclusionThis study provides insights into parents’ perceptions regarding an integrated intervention approach for early stuttering and behavior management. It also indicates how adopting a holistic approach to stuttering intervention is positive and has social validity.     

Two paradoxes in stuttering treatment

The premise of this article is that effective communication should be a central, overarching goal in the treatment of stuttering. Not focusing on communication may have some unintended negative consequences on treatment. The negative consequences are the result of two paradoxes that confront clinicians and clients: the listener paradox and the communication paradox. The listener paradox concerns the different ways that typical listeners and clinicians respond to stuttering. The communication paradox concerns the use of treatment procedures that may have negative consequences on communication. Clinicians and clients need to evaluate treatment procedures in terms of the effect they may have on communication. Understanding these two paradoxes and making effective communication the focus of treatment may improve the long-term treatment outcomes of people who stutter. EDUCATIONAL OBJECTIVES: The reader will learn about (1) why effective communication should be the central goal in the treatment of stuttering; (2) how the listener and communication paradoxes may negatively impact on communication; and (3) how understanding these paradoxes may improve the long-term outcomes of people who stutter and also improve the comfort level clinicians have in treating individuals who stutter.     

Identifying developmental stuttering and associated comorbidities in electronic health records and creating a phenome risk classifier

PurposeThis study aimed to identify cases of developmental stuttering and associated comorbidities in de-identified electronic health records (EHRs) at Vanderbilt University Medical Center, and, in turn, build and test a stuttering prediction model.MethodsA multi-step process including a keyword search of medical notes, a text-mining algorithm, and manual review was employed to identify stuttering cases in the EHR. Confirmed cases were compared to matched controls in a phenotype code (phecode) enrichment analysis to reveal conditions associated with stuttering (i.e., comorbidities). These associated phenotypes were used as proxy variables to phenotypically predict stuttering in subjects within the EHR that were not otherwise identifiable using the multi-step identification process described above.ResultsThe multi-step process resulted in the manually reviewed identification of 1,143 stuttering cases in the EHR. Highly enriched phecodes included codes related to childhood onset fluency disorder, adult-onset fluency disorder, hearing loss, sleep disorders, atopy, a multitude of codes for infections, neurological deficits, and body weight. These phecodes were used as variables to create a phenome risk classifier (PheRC) prediction model to identify additional high likelihood stuttering cases. The PheRC prediction model resulted in a positive predictive value of 83 %.ConclusionsThis study demonstrates the feasibility of using EHRs in the study of stuttering and found phenotypic associations. The creation of the PheRC has the potential to enable future studies of stuttering using existing EHR data, including investigations into the genetic etiology.     

Properties of the maximum likelihood solution in factor analysis regression

Algebraic properties of the normal theory maximum likelihood solution in factor analysis regression are investigated. Two commonly employed measures of the within sample predictive accuracy of the factor analysis regression function are considered: the variance of the regression residuals and the squared correlation coefficient between the criterion variable and the regression function. It is shown that this within sample residual variance and within sample squared correlation may be obtained directly from the factor loading and unique variance estimates, without use of the original observations or the sample covariance matrix.     

Syntactic determinants of stuttering in the spontaneous speech of normally fluent and stuttering children

Conflicting findings have been reported concerning whether fluent children use more complex syntactic structures than stutterers and whether or not stutterers experience specific difficulty with complex syntactic structures. On critical examination, the first of these apparent discrepancies appears to be due to (a) differences in the methods employed for syntactic analysis in different studies, and (b) misleading impressions gained by looking at speakers within a single age range. Data were reanalyzed where one method of analysis had shown that fluent speakers and stutterers did not differ with regard to syntactic structures used but where they did show a propensity for stuttering to occur on complex syntactic structures. These data cover a range of age groups. When the second method of syntactic analysis was applied, a difference was found between fluent speakers and stutterers, with the stutterers initially using more simple structures and fewer complex ones. This difference decreased over age groups. However, a difference still remained with respect to which syntactic structures stutterers experience difficulty. An additional analysis, not formerly conducted on these data, showed that, as reported elsewhere, there was a higher probability of stuttering on clause-initial and. It was also shown that this tendency decreased with age group of the stutterers.