The Trade-Off Between Factor Score Determinacy and the Preservation of Inter-Factor Correlations.

Regression factor score predictors have the maximum factor score determinacy, that is, the maximum correlation with the corresponding factor, but they do not have the same inter-correlations as the factors. As it might be useful to compute factor score predictors that have the same inter-correlations as the factors, correlation-preserving factor score predictors have been proposed. However, correlation-preserving factor score predictors have smaller correlations with the corresponding factors (factor score determinacy) than regression factor score predictors. Thus, higher factor score determinacy goes along with bias of the inter-correlations and unbiased inter-correlations go along with lower factor score determinacy. The aim of the present study was therefore to investigate the size and conditions of the trade-off between factor score determinacy and bias of inter-correlations by means of algebraic considerations and a simulation study. It turns out that under several conditions very small gains of factor score determinacy of the regression factor score predictor go along with a large bias of inter-correlations. Instead of using the regression factor score predictor by default, it is proposed to check whether substantial bias of inter-correlations can be avoided without substantial loss of factor score determinacy using a correlation-preserving factor score predictor. A syntax that allows to compute correlation-preserving factor score predictors from regression factor score predictors, and to compare factor score determinacy and inter-correlations of the factor score predictors is given in the Appendix.

Assessment of Cirrhotic Patients by the EncephalApp Fails to Predict Low-Grade Hepatic Encephalopathy.

INTRODUCTION: An early detection of low-grade hepatic encephalopathy (HE) is of high importance. The aim of the study was to compare a neuropsychological with a psychophysical test on the basis of the psychometric hepatic encephalopathy score (PHES) regarding effectiveness in diagnosing minimal HE (MHE). METHODS: In our prospective controlled observational study, we examined a total of 103 patients with liver cirrhosis for HE. The PHES, CFF, and EncephalApp were performed in all patients. Graduation was based on the result of the PHES. Patients without evidence for HE 1&2 according to the mental state (West-Haven criteria) with a PHES <-4 value points and no clinical symptoms were defined as having MHE. Patients were considered as HE0 when in the PHES none of the psychometric subtest results was abnormal or with a PHES ≥-4 value points. Patients with clinical symptoms were considered HE 1&2 patients. Different cut-off values were determined, and their specificity and sensitivity were calculated. RESULTS: Ninety-six of the involved patients had liver cirrhosis and 25 acted as a healthy control group. The ROC analysis for the classification resulted in an AUC of 0.806, with the highest Youden index for the cut-off time >224 s, for which the sensitivity was 82% and the specificity 75%. Cases of withdrawals were seen in 10.74% of all tested patients. CONCLUSION: The EncephalApp distinguishes well between HE0 and MHE but has its limitations in grading higher forms of HE. Diagnosis using only the EncephalApp is not sufficient.

Men, mindsets and birth: results of a prospective longitudinal study.

AIMS/BACKGROUND: In recent years, there has been an increased interested in the contribution of fathers to childbirth. In the present paper we explore whether the father's birth-related mindset (being either more natural or more medical) can predict the mother's labour and birth outcomes and whether the father's experience and evaluation of the birth can predict his psychological well-being after the birth. DESIGN/METHODS: We conducted a longitudinal study (N = 304 expecting fathers) spanning the first trimester of pregnancy up to six months after birth. RESULTS: The study results could be integrated into a Single Indicator Model. They indicated that a father's more natural birth-related mindset predicted low-intervention birth for the mother. A low-intervention birth led to a more positive birth experience for the father, and in turn to better postpartum adjustment, fewer symptoms of postpartum paternal depression eight weeks after birth, and more secure bonding to the infant six months after birth. CONCLUSION: The study results indicate that fathers do not take a merely passive role in childbirth. On the contrary, analogous to pregnant mothers, fathers' views about childbirth might contribute to the course of birth, and their own postpartum psychological well-being. The results of the present study, thus, highlight the importance of fathers for childbirth and in a broader sense, the results also contribute to a better understanding of the psychological framework of birth and represents a valuable starting point for further research.

Robust oblique Target-rotation for small samples.

Introduction: Oblique Target-rotation in the context of exploratory factor analysis is a relevant method for the investigation of the oblique simple structure. It was argued that minimizing single cross-loadings by means of target rotation may lead to large effects of sampling error on the target rotated factor solutions. Method: In order to minimize effects of sampling error on results of Target-rotation we propose to compute the mean cross-loadings for each block of salient loadings of the independent clusters model and to perform Target-rotation for the block-wise mean cross-loadings. The resulting transformation-matrix is than applied to the complete unrotated loading matrix in order to produce mean Target-rotated factors. Results: A simulation study based on correlated independent clusters model and zero-mean cross-loading models revealed that mean oblique Target-rotation resulted in smaller bias of factor inter-correlations than conventional Target-rotation based on single loadings, especially when sample size was small and when the number of factors was large. An empirical example revealed that the similarity of Target-rotated factors computed for small subsamples with Target-rotated factors of the total sample was more pronounced for mean Target-rotation than for conventional Target-rotation. Discussion: Mean Target-rotation can be recommended in the context of oblique factor models based on simple structure, especially for small samples. An R-script and an SPSS-script for this form of Target-rotation are provided in the Supplementary Material.

Partner support and relationship quality as potential resources for childbirth and the transition to parenthood.

BACKGROUND: The aim of the present paper was to explore the role of partners for the stressful life events of birth and the transition to parenthood. METHODS: In a first prospective longitudinal study (N = 304 dyads) we tested whether relationship quality positively predicted fewer interventions during labor and birth, a more positive birth experience, and better well-being during the first six weeks after birth. In a second study we surveyed mothers (N = 980; retrospective quasi-experimental design) who had given birth during the first lockdown of the COVID-19 pandemic in spring 2020 - some in the absence of their partners - to test the assumption that regardless of relationship quality, the presence of the partner was positively related to low-intervention births and the birth experience. RESULTS: The results of the longitudinal study (Study 1) could be integrated into a Single Indicator model. They revealed that a high relationship quality assessed between week 5 and week 25 of pregnancy had a positive effect on birth experience for the mother and on psychological well-being during the transition to parenthood for both mothers and fathers. Results of the retrospective quasi-experimental field study (Study 2) revealed that the continuous presence of the partner was associated with a higher probability of a low-intervention birth and a more positive birth experience. Presence of a partner for only part of the birth did not positively predict labor and birth, but did positively predict the birth experience. The effects were independent of relationship quality. CONCLUSION: The results of both studies highlight the importance of partners for psychological well-being during labor and birth and the transition to parenthood.

Coefficients of Factor Score Determinacy for Mean Plausible Values of Bayesian Factor Analysis.

In the context of Bayesian factor analysis, it is possible to compute plausible values, which might be used as covariates or predictors or to provide individual scores for the Bayesian latent variables. Previous simulation studies ascertained the validity of mean plausible values by the mean squared difference of the mean plausible values and the generating factor scores. However, the mean correlation of sets of single plausible values of different factors were shown to be an adequate estimator of the correlation between factors. Using sets of single plausible values to compute a mean prediction in secondary analysis implies that their determinacy should be known. Therefore, a plausible value-based determinacy coefficient allowing for estimation of the determinacy of single plausible values was proposed and evaluated by means of two simulation studies. The first simulation study demonstrated that the plausible value-based determinacy coefficient is an adequate estimate of the correlation of single plausible values with the population factor. It is also shown that the plausible value-based determinacy coefficient of mean plausible values approaches the conventional, model parameter-based determinacy coefficient with increasing number of imputations. The second simulation study revealed that the plausible value-based determinacy coefficient and the model parameter-based determinacy coefficient yield similar results even for misspecified models in small samples. It also revealed that for small sample sizes and a small salient loading size, the coefficients of determinacy overestimate the validity, so that it is recommended to report the determinacy coefficients together with a bias-correction to estimate the validity of plausible values in empirical settings.

On the Detection of the Correct Number of Factors in Two-Facet Models by Means of Parallel Analysis.

Methods for optimal factor rotation of two-facet loading matrices have recently been proposed. However, the problem of the correct number of factors to retain for rotation of two-facet loading matrices has rarely been addressed in the context of exploratory factor analysis. Most previous studies were based on the observation that two-facet loading matrices may be rank deficient when the salient loadings of each factor have the same sign. It was shown here that full-rank two-facet loading matrices are, in principle, possible, when some factors have positive and negative salient loadings. Accordingly, the current simulation study on the number of factors to extract for two-facet models was based on rank-deficient and full-rank two-facet population models. The number of factors to extract was estimated from traditional parallel analysis based on the mean of the unreduced eigenvalues as well as from nine other rather traditional versions of parallel analysis (based on the 95th percentile of eigenvalues, based on reduced eigenvalues, based on eigenvalue differences). Parallel analysis based on the mean eigenvalues of the correlation matrix with the squared multiple correlations of each variable with the remaining variables inserted in the main diagonal had the highest detection rates for most of the two-facet factor models. Recommendations for the identification of the correct number of factors are based on the simulation results, on the results of an empirical example data set, and on the conditions for approximately rank-deficient and full-rank two-facet models.

Score Predictor Factor Analysis: Reproducing Observed Covariances by Means of Factor Score Predictors.

The non-diagonal elements of the observed covariances are more exactly reproduced by the factor loadings than by the model implied by the corresponding factor score predictors. This is a limitation to the validity of factor score predictors. It is therefore investigated whether it is possible to estimate factor loadings for which the model implied by the factor score predictors optimally reproduces the non-diagonal elements of the observed covariance matrix. Accordingly, loading estimates are proposed for which the model implied by the factor score predictors allows for a least-squares approximation of the non-diagonal elements of the observed covariance matrix. This estimation method is termed score predictor factor analysis and algebraically compared with Minres factor analysis as well as principal component analysis. A population-based and a sample-based simulation study was performed in order to compare score predictor factor analysis, Minres factor analysis, and principal component analysis. It turns out that the non-diagonal elements of the observed covariance matrix can more exactly be reproduced from the factor score predictors computed from score predictor factor analysis than from the factor score predictors computed from Minres factor analysis and from principal components.

Efficacy of l-Ornithine l-Aspartate for the Treatment of Hepatic Encephalopathy and Hyperammonemia in Cirrhosis: Systematic Review and Meta-Analysis of Randomized Controlled Trials.

BACKGROUND/OBJECTIVES: l-Ornithine l-Aspartate (LOLA) is a mixture of two endogenous amino acids with the capacity to fix ammonia in the form of urea and/or glutamine. Its' efficacy for the treatment of Hepatic Encephalopathy (HE), a known hyperammonemic disorder, remains the subject of debate. This study quantitatively analyzed the efficacy of LOLA in patients with cirrhosis and HE. METHODS: Efficacy was defined as the extent of lowering of blood ammonia and improvement of mental state assessed in clinically overt HE (OHE) by Westhaven criteria or psychometric testing for assessment of Minimal HE (MHE). Appropriate keywords were used for electronic and/or manual searches of databases to identify RCTs for inclusion. Study quality and risk of bias were assessed using the Jadad Composite Scale together with The Cochrane Scoring Tool. Random Effects Models were used to express pooled Risk Ratio (RR) or Mean Difference (MD) with associated 95% Confidence Intervals (CI). RESULTS: 10 RCTs (884 patients) were included. Regression analysis showed no evidence of publication bias or other small study effects. Eight RCTs had low risk of bias by Jadad/Cochrane criteria. Comparison with placebo/no intervention controls revealed that LOLA was significantly more effective for improvement of mental state in all types of HE (RR 1.36 (95% CI 1.10-1.69), p = 0.005), OHE (RR: 1.19, 95% CI of 1.01-1.39, test for overall effect: Z = 2.14, p = 0.03), MHE (RR: 2.15 (1.48-3.14), p < 0.0001) and for lowering of blood ammonia (MD: -17.50 µmol/l (-27.73 to (-7.26)), p = 0.0008). Improvement of mental state was greater in trials with low risk of bias. Heterogeneity was reduced in trials from Europe or with >100 participants. Oral LOLA appeared particularly effective for the treatment of MHE. CONCLUSION: LOLA appears to improve mental state and lower ammonia in patients with HE or MHE. Further studies are required in some subgroups of HE and in the era of HE reclassification.

Extending the Debate Between Spearman and Wilson 1929: When do Single Variables Optimally Reproduce the Common Part of the Observed Covariances?

The covariances of observed variables reproduced from conventional factor score predictors are generally not the same as the covariances reproduced from the common factors. We sought to find a factor score predictor that optimally reproduces the common part of the observed covariances. It was found algebraically that-under some conditions-the single observed variable with highest loading on a factor reproduces the non-diagonal elements of the observed covariance matrix more exactly than the conventional factor score predictors. This finding is linked to Spearman's and Wilson's 1929 debate on the use of single variables as factor score predictors. A population-based and a sample-based simulation study confirmed the algebraic result that taking a single variable can outperform conventional factor score predictors in reproducing the non-diagonal covariances when the nonzero loading size and the number of nonzero loadings per factor are small. The results indicated that a weighted aggregation of variables does not necessarily lead to an improvement of the score over the variable with the highest loading.

Value of critical flicker frequency and psychometric hepatic encephalopathy score in diagnosis of low-grade hepatic encephalopathy.

BACKGROUND & AIMS: Critical flicker frequency (CFF) and psychometric hepatic encephalopathy score (PHES) analyses are widely used to diagnose hepatic encephalopathy (HE), but little is known about their value in the diagnosis of low-grade HE. METHODS: The diagnostic values of CFF and PHES were compared using a computerized test battery and West Haven criteria as reference. We performed CFF analysis on 559 patients with cirrhosis and 261 without (controls). Of these 820 patients, 448 were evaluated using a modified PHES system and 148 were also evaluated using the conventional PHES system. RESULTS: CFF distinguished between patients with overt HE and without minimal or overt HE in the entire study population with 98% sensitivity and 94% specificity and in the subgroup of patients who were evaluated by conventional PHES with 97% sensitivity and 100% specificity. Conventional PHES identified patients with overt HE with 73% sensitivity and 89% specificity. CFF distinguished between patients with and without minimal HE with only 37% sensitivity but 94% specificity (entire study population). In the subgroup of patients evaluated by conventional PHES, CFF distinguished between patients with and without minimal HE with 22% sensitivity and 100% specificity; these values were similar to those for conventional PHES (30% sensitivity and 89% specificity). The modified PHES distinguished between patients with and without minimal HE with 49% sensitivity and 74% specificity. The diagnostic agreement values between CFF and conventional or modified PHES in patients with minimal HE were only 54% or 47%, respectively. CONCLUSIONS: In an analysis of patients with cirrhosis and controls, CFF distinguished between patients with overt HE and without minimal or overt HE. PHES testing produced a statistically significant difference among groups, but there was considerable overlap between controls and patients with overt HE. PHES, CFF, and a combination of PHES and CFF could not reliably distinguish patients with minimal HE from controls or those with overt HE.

Diagnostic and prognostic values of critical flicker frequency determination as new diagnostic tool for objective HE evaluation in patients undergoing TIPS implantation.

OBJECTIVES: The diagnostic and prognostic value of critical flicker frequency (CFF) analysis for assessment of severity and dynamics of hepatic encephalopathy (HE) was studied before and after implantation of a transjugular intrahepatic portosystemic shunt (TIPS). BASIC METHODS: Sixty-three cirrhotic patients were retrospectively analyzed for the consequences of TIPS implantation. Thirty-one cirrhotic patients without TIPS implantation served as age-matched, sex-matched, Child-Pugh-matched controls. CFF and computer psychometric tests as objective test parameters of HE-severity were evaluated for analysis of visual discrimination ability, general arousal and cognitive function. Kaplan-Meier method and Cox proportional hazards regression model were used for analysis of prognostic significances. MAIN RESULTS: In the control group, HE-severity was stable during the observation period (442+/-428 days) with minimal changes in CFF (-0.1+/-1.9 Hz). In the intervention group, TIPS implantation had no effect on HE-severity in 44% of the patients and CFF shifted by only 0.01+/-1.5 Hz. Thirty-five and 21% of the patients experienced an aggravation or improvement of HE after TIPS implantation, respectively. In HE improvers CFF increased by 3.3+/-2.3 Hz and decreased by 3.5+/-1.5 Hz in those experiencing an aggravation of HE-severity. Univariate analysis showed that overall survival in the study population inversely correlated with HE-severity and serum alkaline phosphatase activity and positively correlated with serum sodium, albumin and CFF. Serum albumin, alkaline phosphatase levels and CFF were independent predictors of survival in a multivariate Cox regression analysis. CONCLUSION: The data show that pre-TIPS HE does not predict post-TIPS encephalopathy. Otherwise, CFF can reliably pick up the evolution of HE-severity after TIPS implantation. Low pre-TIPS CFF is indicative for a poor prognosis and may help to identify transplant candidates without delay.

Hepatic encephalopathy and fitness to drive.

BACKGROUND & AIMS: Low-grade hepatic encephalopathy (HE) may impair fitness to drive. Driving deficits have not yet been characterized, and their relation to psychometric test results is unclear. METHODS: Fifty-one cirrhotic patients and 48 age-matched controls underwent real driving in a multiple sensor and camera-equipped car, laboratory and "in-car" computer psychometry, and driving instructor's assessment. RESULTS: Ten cirrhotic patients had no hepatic encephalopathy (HE0); 27 and 14 patients suffered from minimal HE (mHE) and overt HE grade I (oHE), respectively. During real driving, mHE and oHE patients showed significantly more violations of in-lane keeping, reduced break use, prolonged reaction times, and diminished stress tolerance compared with control or cirrhotic HE0 patients. In a self-evaluation questionnaire, mHE and oHE, but not the HE0, patients strongly overestimated their driving abilities. According to the driving instructor's assessment, 75%, 48%, and 39% of the patients with HE0, mHE, and oHE, respectively, were fit to drive, compared with 87% in the control group. Driving deficits in oHE patients were largely due to cognitive defects and prolonged reaction times, whereas, in mHE patients, mistakes and attention deficits predominated. Computer psychometric test results worsened with HE severity and age, whereas real driving was age independent. In 25 out of 94 patients, discordant results for driving fitness were obtained (driving instructor's assessment vs computer psychometry); in mHE and oHE patients, the concordance rates were only 62% and 64%, respectively. CONCLUSIONS: Despite significant driving deficits, HE patients overestimate their driving abilities. The presence of mHE does not necessarily predict driving unfitness, and computer-based testings cannot reliably predict driving fitness.