Factorial experiments in research on memory, language, and in other areas are often analyzed using analysis of variance (ANOVA). However, for effects with more than one numerator degrees of freedom, e.g., for experimental factors with more than two levels, the ANOVA omnibus F-test is not informative about the source of a main effect or interaction.Because researchers typically have specific hypotheses about which condition means differ from each other, a priori contrasts (i.e., comparisons planned before the sample means are known) between specific conditions or combinations of conditions are the appropriate way to represent such hypotheses in the statistical model. Many researchers have pointed out that contrasts should be "tested instead of, rather than as a supplement to, the ordinary 'omnibus' F test" (Hays, 1973, p. 601). In this tutorial, we explain the mathematics underlying different kinds of contrasts (i.e., treatment, sum, repeated, polynomial, custom, nested, interaction contrasts), discuss their properties, and demonstrate how they are applied in the R System for Statistical Computing (R Core Team, 2018). In this context, we explain the generalized inverse which is needed to compute the coefficients for contrasts that test hypotheses that are not covered by the default set of contrasts. A detailed understanding of contrast coding is crucial for successful and correct specification in linear models (including linear mixed models). Contrasts defined a priori yield far more useful confirmatory tests of experimental hypotheses than standard omnibus F-test.
Word features in parafoveal vision influence eye movements during reading. The question of whether readers extract semantic information from parafoveal words was studied in 3 experiments by using a gaze-contingent display change technique. Subjects read German sentences containing 1 of several preview words that were replaced by a target word during the saccade to the preview (boundary paradigm). In the 1st experiment the preview word was semantically related or unrelated to the target. Fixation durations on the target were shorter for semantically related than unrelated previews, consistent with a semantic preview benefit. In the 2nd experiment, half the sentences were presented following the rules of German spelling (i.e., previews and targets were printed with an initial capital letter), and the other half were presented completely in lowercase. A semantic preview benefit was obtained under both conditions. In the 3rd experiment, we introduced 2 further preview conditions, an identical word and a pronounceable nonword, while also manipulating the text contrast. Whereas the contrast had negligible effects, fixation durations on the target were reliably different for all 4 types of preview. Semantic preview benefits were greater for pretarget fixations closer to the boundary (large preview space) and, although not as consistently, for long pretarget fixation durations (long preview time). The results constrain theoretical proposals about eye movement control in reading. (PsycINFO Database Record (c) 2013 APA, all rights reserved).
Eye-movement control during reading depends on foveal and parafoveal information. If the parafoveal preview of the next word is suppressed, reading is less efficient. A linear mixed model (LMM) reanalysis of McDonald (2006) confirmed his observation that preview benefit may be limited to parafoveal words that have been selected as the saccade target. Going beyond the original analyses, in the same LMM, we examined how the preview effect (i.e., the difference in single-fixation duration, SFD, between random-letter and identical preview) depends on the gaze duration on the pretarget word and on the amplitude of the saccade moving the eye onto the target word. There were two key results: (a) The shorter the saccade amplitude (i.e., the larger preview space), the shorter a subsequent SFD with an identical preview; this association was not observed with a random-letter preview. (b) However, the longer the gaze duration on the pretarget word, the longer the subsequent SFD on the target, with the difference between random-letter string and identical previews increasing with preview time. A third pattern-increasing cost of a random-letter string in the parafovea associated with shorter saccade amplitudes-was observed for target gaze durations. Thus, LMMs revealed that preview effects, which are typically summarized under "preview benefit", are a complex mixture of preview cost and preview benefit and vary with preview space and preview time. The consequence for reading is that parafoveal preview may not only facilitate, but also interfere with lexical access.
With the arrival of the R packages nlme and lme4, linear mixed models (LMMs) have come to be widely used in experimentally-driven areas like psychology, linguistics, and cognitive science. This tutorial provides a practical introduction to fitting LMMs in a Bayesian framework using the probabilistic programming language Stan. We choose Stan (rather than WinBUGS or JAGS) because it provides an elegant and scalable framework for fitting models in most of the standard applications of LMMs. We ease the reader into fitting increasingly complex LMMs, using a twocondition repeated measures self-paced reading study.
Eye movements in reading are sensitive to foveal and parafoveal word features. Whereas the influence of orthographic or phonological parafoveal information on gaze control is undisputed, there has been no reliable evidence for early parafoveal extraction of semantic information in alphabetic script. Using a novel combination of the gaze-contingent fast-priming and boundary paradigms, we demonstrate semantic preview benefit when a semantically related parafoveal word was available during the initial 125 ms of a fixation on the pretarget word (Experiments 1 and 2). When the target location was made more salient, significant parafoveal semantic priming occurred only at 80 ms (Experiment 3). Finally, with short primes only (20, 40, 60 ms), effects were not significant but were numerically in the expected direction for 40 and 60 ms (Experiment 4). In all experiments, fixation durations on the target word increased with prime durations under all conditions. The evidence for extraction of semantic information from the parafoveal word favors an explanation in terms of parallel word processing in reading.
Aims The coronavirus disease 2019 (COVID‐19) pandemic has led to changes in health care utilization for different acute cardiovascular diseases. Whether hospitalization rates and in‐hospital mortality were affected by the pandemic in patients with acute symptomatic heart failure (HF) was investigated in this study. Methods and results Administrative data provided by 67 German Helios hospitals were examined for patients with a main discharge diagnosis of HF using ICD codes. Urgent hospital admissions per day were compared for a study period (13 March–21 May 2020) with control intervals in 2020 (1 January–12 March) and 2019 (13 March–21 May), resulting in a total of 13 484 patients excluding all patients with laboratory‐proven COVID‐19 infection. Incidence rate ratios (IRR) were calculated using Poisson regression. Generalized linear mixed models were used for univariable and multivariable analysis to identify predictors of in‐hospital mortality. The number of admissions per day was lower in the study period compared to the same year [IRR 0.69, 95% confidence interval (CI) 0.67–0.73, P < 0.01] and the previous year control group (IRR 0.73, 95% CI 0.70–0.76, P < 0.01). Age was similar throughout the intervals, but case severity increased in terms of distribution within New York Heart Association (NYHA) classes and comorbidities. Within the study period, 30‐day rates for urgent hospital readmissions were higher compared to the same year but not the previous year control group. In‐hospital mortality was 7.3% in the study period, 6.1% in the same year (P = 0.03) and 6.0% in the previous year control group (P = 0.02). In multivariable analysis, age, NYHA class and other predictors of fatal outcome were identified but hospitalization during the study period was not independently associated with mortality. Conclusion Our data showed a significant reduction of urgent hospital admissions for HF with increased case severity and concomitant in‐hospital mortality during the COVID‐19 pandemic in Germany. Identifying causes of reduced inpatient treatment rates is essential for the understanding and valuation with regard to future optimal management of patients with HF.
Background: Transcatheter aortic valve replacement (TAVR) is an established treatment option for patients with severe symptomatic aortic stenosis (AS), and is most commonly performed through the transfemoral access route. Percutaneous access site closure can be achieved using dedicated plug-based or suture-based vascular closure device (VCD) strategies, but randomized comparative studies are scarce. Methods: The CHOICE-CLOSURE (Randomized Comparison of CatHeter-based Strategies fOr Interventional ACcess SitE CLOSURE during Transfemoral Transcatheter Aortic Valve Implantation) trial is an investigator-initiated, multicenter study, in which patients undergoing transfemoral TAVR were randomly assigned to vascular access site closure using either a pure plug-based technique (MANTA, Teleflex, Wayne, Pennsylvania) with no additional VCDs or a primary suture-based technique (ProGlide, Abbott Vascular, Abbott Park, Illinois) potentially complemented by a small-plug. The primary endpoint consisted of access-site or access-related major and minor vascular complications during index hospitalization, defined according to the Valve Academic Research Consortium-2 criteria. Secondary endpoints included the rate of access-site or access-related bleeding, VCD failure, and time to hemostasis Results: A total of 516 patients were included and randomized. The mean age of the study population was 80.5±6.1 years, 55.4% were male, 7.6% of patients had peripheral vascular disease, and the mean Society of Thoracic Surgeons score was 4.1±2.9%. The primary endpoint occurred in 19.4% (50/258) of the pure plug-based group and 12.0% (31/258) of the primary suture-based group (relative risk [RR]: 1.61, 95% confidence interval [CI]: 1.07-2.44, p=0.029). Access-site or access-related bleeding occurred in 11.6% vs. 7.4% (RR: 1.58, 95%CI: 0.91-2.73, p=0.133) and device failure in 4.7% vs. 5.4% (RR: 0.86, 95%CI: 0.40-1.82, p=0.841) in the respective groups. Time to hemostasis was significantly shorter in the pure plug-based group (80 [32, 180] vs. 240 [174, 316] seconds, p<0.001). Conclusions: Among patients treated with transfemoral TAVR, a pure plug-based vascular closure technique using the MANTA VCD is associated with a higher rate of access-site or access-related vascular complications but a shorter time to hemostasis compared to a primary suture-based technique using the ProGlide VCD.
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