scholarly journals A note on the bias of standard errors when orthogonality of mean and variance parameters is not satisfied in the mixed model for repeated measures analysis

2020 ◽  
Vol 39 (9) ◽  
pp. 1264-1274 ◽  
Author(s):  
Kazushi Maruo ◽  
Ryota Ishii ◽  
Yusuke Yamaguchi ◽  
Masaaki Doi ◽  
Masahiko Gosho
Keyword(s):  
Repeated Measures ◽  
Mixed Model ◽  
Standard Errors ◽  
Repeated Measures Analysis ◽  
Mean And Variance ◽  
Variance Parameters

scholarly journals Mood and Global Symptom Changes among Psychotherapy Clients with Depressive Personality

2012 ◽  
Vol 2012 ◽  
pp. 1-12
Author(s):  
Rachel E. Maddux ◽  
Lars-Gunnar Lundh
Keyword(s):  
Repeated Measures ◽  
Mixed Model ◽  
Psychological Symptoms ◽  
Self Report ◽  
Treatment Results ◽  
Repeated Measures Analysis ◽  
Depressive Personality ◽  
Symptom Changes ◽  
Psychotherapy Clients ◽  
Over Time

The present study assessed the rate of depressive personality (DP), as measured by the self-report instrument depressive personality disorder inventory (DPDI), among 159 clients entering psychotherapy at an outpatient university clinic. The presenting clinical profile was evaluated for those with and without DP, including levels of depressed mood, other psychological symptoms, and global severity of psychopathology. Clients were followed naturalistically over the course of therapy, up to 40 weeks, and reassessed on these variables again after treatment. Results indicated that 44 percent of the sample qualified for DP prior to treatment, and these individuals had a comparatively more severe and complex presenting disposition than those without DP. Mixed-model repeated-measures analysis of variance was used to examine between-groups changes on mood and global severity over time, with those with DP demonstrating larger reductions on both outcome variables, although still showing more symptoms after treatment, than those without DP. Only eleven percent of the sample continued to endorse DP following treatment. These findings suggest that in routine clinical situations, psychotherapy may benefit individuals with DP.

Music and mindfulness meditation: Comparing four music stimuli composed under similar principles

2020 ◽  
pp. 030573562096979
Author(s):  
Eugenia Hernandez-Ruiz ◽  
Abbey L Dvorak
Keyword(s):  
Repeated Measures ◽  
Mixed Model ◽  
Mindfulness Meditation ◽  
New Music ◽  
Original Music ◽  
Evidence Based ◽  
Supporting Evidence ◽  
Significant Preference ◽  
Repeated Measures Analysis ◽  
Significant Difference

Mindfulness meditation has frequently used sound and music as an important component. However, research on effective music stimuli is scarce. After a series of studies evaluating the most effective, useful, and preferred auditory stimuli, we were interested in exploring whether these effective musical features were transferred to new music. In this study, we evaluate our original music stimuli with three new stimuli composed under similar principles. Non-musician and musician participants ( N = 114) in a multisite study evaluated their mindfulness state after listening to four music stimuli, and rated their usefulness and preference. Results from a repeated-measures analysis of variance (ANOVA) at each site indicated no significant difference in mindfulness effectiveness. Friedman’s ANOVAs for the usefulness of the music stimuli showed similar non-significant results in both sites. A mixed model among sites did not show significant differences among groups. Preference rankings were not significantly different for non-musicians, but musicians did show a statistically significant preference of the Original stimuli over Stimulus 2, probably due to sound quality. These results indicate the feasibility of transferring previously researched and effective musical features to new stimuli. Identifying the effective “active ingredients” of music interventions may be one way of supporting evidence-based practice in music therapy.

scholarly journals Determinants of Ceftazidime Clearance by Continuous Venovenous Hemofiltration and Continuous Venovenous Hemodialysis

2000 ◽  
Vol 44 (6) ◽  
pp. 1639-1644 ◽  
Author(s):  
Gary R. Matzke ◽  
Reginald F. Frye ◽  
Melanie S. Joy ◽  
Paul M. Palevsky
Keyword(s):  
Repeated Measures ◽  
High Performance ◽  
Mixed Model ◽  
Random Effect ◽  
Quantitative Information ◽  
Continuous Venovenous Hemofiltration ◽  
Linear Relationships ◽  
Repeated Measures Analysis ◽  
Continuous Venovenous Hemodialysis ◽  
Dosing Strategies

ABSTRACT Although several dosage adjustment regimens have been proposed, there is little quantitative information to guide the initiation of ceftazidime therapy in patients who are receiving continuous renal replacement therapy. To determine the clearance of ceftazidime by continuous venovenous hemofiltration (CVVH) and continuous venovenous hemodialysis (CVVHD), we performed controlled clearance studies with stable hemodialysis patients with three hemofilters: a 0.6-m2 acrylonitrile copolymer (AN69; Hospal) filter, a 2.1-m2 polymethylmethacrylate filter (PMMA; Toray) filter and a 0.65-m2 polysulfone (PS; Fresenius) filter. Subjects received 1,000 mg of ceftazidime intravenously prior to the start of a clearance study. The concentration of ceftazidime in multiple plasma and dialysate or ultrafiltrate samples was determined by high-performance liquid chromatography. The diffusional clearances (CIdiffusion) and sieving coefficients of ceftazidime were compared by a mixed-model repeated-measures analysis of variance with filter and blood, dialysate inflow, or ultrafiltration rate as the main effect and the patient as a random effect. The fraction of ceftazidime bound to plasma proteins was 17% ± 7% (range, 10 to 25%). The clearances of ceftazidime, urea, and creatinine by CVVHD were essentially constant at blood flow rates of 75 to 250 ml/min for all three filters. Significant linear relationships (P < 0.0001) were observed between CIdiffusion of ceftazidime and clearance of urea for all three filters: AN69 (slope = 0.83), PMMA (slope = 0.89), and PS (slope = 1.03). Ceftazidime clearance was membrane independent during CVVH and CVVHD. CVVH and CVVHD can significantly augment the clearance of ceftazidime. Dosing strategies for initiation of ceftazidime therapy in patients receiving CVVH and CVVHD are proposed.

Linear mixed model better than repeated measures analysis

2019 ◽  
Vol 30 (6) ◽  
pp. NP1-NP2 ◽  
Author(s):  
Işıl Kutluturk Karagoz ◽  
Berhan Keskin ◽  
Flora Özkalaycı ◽  
Ali Karagöz
Keyword(s):  
Mixed Models ◽  
Repeated Measures ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Linear Time ◽  
Case Series ◽  
Model Fit ◽  
Repeated Measures Analysis ◽  
Technical Issues ◽  
Better Than

We have some criticism regarding some technical issues. Mixed models have begun to play a pivotal role in statistical analyses and offer many advantages over more conventional analyses regarding repeated variance analyses. First, they allow to avoid conducting multiple t-tests; second, they can accommodate for within-patient correlation; third, they allow to incorporate not only a random coefficient, but also a random slope, typically ‘linear’ time in longitudinal case series when there are enough data and patients’ trajectories vary a lot and improving model fit.

scholarly journals Oxytocin and Oxytocinase in the Obese and Nonobese Parturients during Induction and Augmentation of Labor

2019 ◽  
Vol 09 (02) ◽  
pp. e177-e184
Author(s):  
Annemaria De Tina ◽  
Jeremy Juang ◽  
Thomas F. McElrath ◽  
Jack D. Baty ◽  
Arvind Palanisamy
Keyword(s):  
Repeated Measures ◽  
Mixed Model ◽  
Group Versus ◽  
Preliminary Evidence ◽  
Analysis Of Covariance ◽  
Uterine Contractions ◽  
Time Interaction ◽  
Repeated Measures Analysis ◽  
Elective Induction ◽  
The Mean

Objective To investigate differences in oxytocin (OXT) biodistribution between nonobese and obese parturients during labor. Study Design Patients with body mass index (BMI) of either ≥ 18 ≤ 24.9 kg/m2 (“nonobese”) or ≥ 30 kg/m2 (“obese”) undergoing elective induction of labor were included (N = 25 each). Blood samples were collected at baseline (T0), and 20 minutes after maximal OXT augmentation or adequate uterine contractions (T1) for OXT and oxytocinase assays. A mixed-model repeated-measures analysis of variance was used to test for group versus time interaction and analysis of covariance to detect a difference in OXT level at T1. Data presented as mean ± standard deviation or median (interquartile range), with p < 0.05 considered significant. Results The mean BMIs (kg/m2) were 22.1 ± 1.6 and 35.9 ± 5.1 in the nonobese and obese groups, respectively. No differences were observed in either the duration of OXT infusion, total dose of OXT, or plasma OXT (pg/mL) either at T0 or T1. However, plasma oxytocinase (ng/mL) was significantly lower at T0 (1.41 [0.67, 3.51] vs. 0.40 [0.29, 1.12]; p = 0.03) in the obese group. Conclusion We provide preliminary evidence that the disposition of OXT may not be different between obese and nonobese women during labor.

scholarly journals Intraindividual variation of dose parameters in oncologic CT imaging

PLoS ONE ◽  
2021 ◽  
Vol 16 (4) ◽  
pp. e0250490
Author(s):  
Isabel Lange ◽  
Babak Alikhani ◽  
Frank Wacker ◽  
Hans-Juergen Raatschen
Keyword(s):  
Radiation Dose ◽  
Iterative Reconstruction ◽  
Repeated Measures ◽  
Mixed Model ◽  
Chest Ct ◽  
Pitch Factor ◽  
Imaging Parameters ◽  
Repeated Measures Analysis ◽  
Tube Current ◽  
Scan Length

The objective of this study is to identify essential aspects influencing radiation dose in computed tomography [CT] of the chest, abdomen and pelvis by intraindividual comparison of imaging parameters and patient related factors. All patients receiving at least two consecutive CT examinations for tumor staging or follow-up within a period of 22 months were included in this retrospective study. Different CT dose estimates (computed tomography dose index [CTDIvol], dose length product [DLP], size-specific dose estimate [SSDE]) were correlated with patient’s body mass index [BMI], scan length and technical parameters (tube current, tube voltage, pitch, noise level, level of iterative reconstruction). Repeated-measures-analysis was initiated with focus on response variables (CTDIvol, DLP, SSDE) and possible factors (age, BMI, noise, scan length, peak kilovoltage [kVp], tube current, pitch, adaptive statistical iterative reconstruction [ASIR]). A univariate-linear-mixed-model with repeated-measures-analysis followed by Bonferroni adjustments was used to find associations between CT imaging parameters, BMI and dose estimates followed by a subsequent multivariate-mixed-model with repeated-measures-analysis with Bonferroni adjustments for significant parameters. A p-value <0.05 was considered statistically significant. We found all dose estimates in all imaging regions were substantially affected by tube current. The iterative reconstruction significantly influenced all dose estimates in the thoracoabdominopelvic scans as well as DLP and SSDE in chest-CT. Pitch factor affected all dose parameters in the thoracoabdominopelvic CT group. These results provide further evidence that tube current has a pivotal role and potential in radiation dose management. The use of iterative reconstruction algorithms can substantially decrease radiation dose especially in thoracoabdominopelvic and chest-CT-scans. Pitch factor should be kept at a level of ≥1.0 in order to reduce radiation dose.

scholarly journals Changes in English Past Tense Use by Bilingual School-Age Children With and Without Developmental Language Disorder

2018 ◽  
Vol 61 (10) ◽  
pp. 2532-2546 ◽  
Author(s):  
Peggy F. Jacobson ◽  
Yan H. Yu
Keyword(s):  
Analysis Of Variance ◽  
Repeated Measures ◽  
Mixed Model ◽  
Language Disorder ◽  
School Age Children ◽  
Past Tense ◽  
The Novel ◽  
Developmental Language Disorder ◽  
Ability Group ◽  
Repeated Measures Analysis

PurposeThe purpose of this study is to examine changes in English past tense accuracy and errors among Spanish–English bilingual children with typical development (TD) and developmental language disorder (DLD).MethodThirty-three children were tested before and after 1 year to examine changes in clinically relevant English past tense errors using an elicited production task. A mixed-model linear regression using age as a continuous variable revealed a robust effect for age. A 4-way repeated-measures analysis of variance was conducted with age (young, old) and language ability group (TD, DLD) as between-subjects variables, time (Time 1, Time 2) and verb type (regular, irregular, and novel verbs) as within-subject variables, and percent accuracy as the dependent variable. Subsequently, a 4-way repeated-measures analysis of variance was conducted to measure the overall distribution of verb errors across 2 time points.ResultsOverall, children produced regular and novel verb past tense forms with higher accuracy than irregular past tense verbs in an elicitation task. Children with TD were more accurate than children with DLD. Younger children made more improvement than older children from Time 1 to Time 2, especially in the regular and novel verb conditions. Bare stem and overregularization were the most common errors across all groups. Errors consisting of stem + ing were more common in children with DLD than those with TD in the novel verb condition.DiscussionContrary to an earlier report (Jacobson & Schwartz, 2005), the relative greater difficulty with regular and novel verbs was replaced by greater difficulty for irregular past tense, a pattern consistent with monolingual impairment. Age was a contributing factor, particularly for younger children with DLD who produced more stem + ing errors in the novel verb condition. For all children, and particularly for those with DLD, an extended period for irregular past tense learning was evident. The results support a usage-based theory of language acquisition and impairment.

Effects of Aging on the Subcortical Encoding of Stop Consonants

2020 ◽  
Vol 29 (3) ◽  
pp. 391-403
Author(s):  
Dania Rishiq ◽  
Ashley Harkrider ◽  
Cary Springer ◽  
Mark Hedrick
Keyword(s):  
Older Adults ◽  
Repeated Measures ◽  
Mixed Model ◽  
Auditory Brainstem ◽  
Auditory Brainstem Responses ◽  
Aging Effects ◽  
Formant Frequency ◽  
Place Of Articulation ◽  
Second Formant ◽  
Effects Of Aging

Purpose The main purpose of this study was to evaluate aging effects on the predominantly subcortical (brainstem) encoding of the second-formant frequency transition, an essential acoustic cue for perceiving place of articulation. Method Synthetic consonant–vowel syllables varying in second-formant onset frequency (i.e., /ba/, /da/, and /ga/ stimuli) were used to elicit speech-evoked auditory brainstem responses (speech-ABRs) in 16 young adults ( M age = 21 years) and 11 older adults ( M age = 59 years). Repeated-measures mixed-model analyses of variance were performed on the latencies and amplitudes of the speech-ABR peaks. Fixed factors were phoneme (repeated measures on three levels: /b/ vs. /d/ vs. /g/) and age (two levels: young vs. older). Results Speech-ABR differences were observed between the two groups (young vs. older adults). Specifically, older listeners showed generalized amplitude reductions for onset and major peaks. Significant Phoneme × Group interactions were not observed. Conclusions Results showed aging effects in speech-ABR amplitudes that may reflect diminished subcortical encoding of consonants in older listeners. These aging effects were not phoneme dependent as observed using the statistical methods of this study.

Power of Modified Brown-Forsythe and Mixed-Model Approaches in Split-Plot Designs

Methodology ◽  
2017 ◽  
Vol 13 (1) ◽  
pp. 9-22 ◽  
Author(s):  
Pablo Livacic-Rojas ◽  
Guillermo Vallejo ◽  
Paula Fernández ◽  
Ellián Tuero-Herrero
Keyword(s):  
Repeated Measures ◽  
Statistical Power ◽  
Mixed Model ◽  
Covariance Structure ◽  
Simulation Method ◽  
Future Research ◽  
Repeated Measures Design ◽  
Fixed And Random Effects ◽  
Split Plot ◽  
High Level

Abstract. Low precision of the inferences of data analyzed with univariate or multivariate models of the Analysis of Variance (ANOVA) in repeated-measures design is associated to the absence of normality distribution of data, nonspherical covariance structures and free variation of the variance and covariance, the lack of knowledge of the error structure underlying the data, and the wrong choice of covariance structure from different selectors. In this study, levels of statistical power presented the Modified Brown Forsythe (MBF) and two procedures with the Mixed-Model Approaches (the Akaike’s Criterion, the Correctly Identified Model [CIM]) are compared. The data were analyzed using Monte Carlo simulation method with the statistical package SAS 9.2, a split-plot design, and considering six manipulated variables. The results show that the procedures exhibit high statistical power levels for within and interactional effects, and moderate and low levels for the between-groups effects under the different conditions analyzed. For the latter, only the Modified Brown Forsythe shows high level of power mainly for groups with 30 cases and Unstructured (UN) and Autoregressive Heterogeneity (ARH) matrices. For this reason, we recommend using this procedure since it exhibits higher levels of power for all effects and does not require a matrix type that underlies the structure of the data. Future research needs to be done in order to compare the power with corrected selectors using single-level and multilevel designs for fixed and random effects.

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