scholarly journals Analyzing randomized controlled interventions: Three notes for applied linguists

2015 ◽  
Vol 5 (1) ◽  
pp. 135-152 ◽  
Author(s):  
Jan Vanhove
Keyword(s):  
Repeated Measures ◽  
Intervention Studies ◽  
Mixed Effects ◽  
Analysis Of Covariance ◽  
Cluster Randomization ◽  
Repeated Measures Anova ◽  
Randomized Controlled ◽  
Mixed Effects Modeling ◽  
Statistical Formalism ◽  
Relevant Covariates

I discuss three common practices that obfuscate or invalidate the statistical analysis of randomized controlled interventions in applied linguistics. These are (a) checking whether randomization produced groups that are balanced on a number of possibly relevant covariates, (b) using repeated measures ANOVA to analyze pretest-posttest designs, and (c) using traditional significance tests to analyze interventions in which whole groups were assigned to the conditions (cluster randomization). The first practice is labeled superfluous, and taking full advantage of important covariates regardless of balance is recommended. The second is needlessly complicated, and analysis of covariance is recommended as a more powerful alternative. The third produces dramatic inferential errors, which are largely, though not entirely, avoided when mixed-effects modeling is used. This discussion is geared towards applied linguists who need to design, analyze, or assess intervention studies or other randomized controlled trials. Statistical formalism is kept to a minimum throughout.

scholarly journals Randomized Controlled Trial of Sealed In-Office Bleaching Effectiveness

2014 ◽  
Vol 25 (3) ◽  
pp. 207-211 ◽  
Author(s):  
Mário Artur Pereira Santana ◽  
Flávia Pardo Salata Nahsan ◽  
Alaíde Hermínia de Aguiar Oliveira ◽  
Alessandro Dourado Loguércio ◽  
André Luis Faria-e-Silva
Keyword(s):  
Repeated Measures ◽  
Absolute Risk ◽  
Controlled Trial ◽  
Tooth Sensitivity ◽  
Repeated Measures Anova ◽  
Randomized Controlled ◽  
Randomized Clinical Study ◽  
Bleaching Procedure ◽  
Significant Difference ◽  
The Absolute

Regardless of the high success rate, patients commonly report the occurrence of tooth sensitivity during the in-office bleaching procedures. Recently, it has been demonstrated that using a customized tray (called sealed in-office bleaching technique) reduces peroxide penetration. The aim of this randomized clinical study was to evaluate tooth sensitivity and bleaching efficacy of sealed bleaching, in comparison with a conventional in-office technique. Twenty patients were randomized allocated in two groups in which 35% hydrogen peroxide gel was used in a single 45-min application. For the sealed technique, a customized bleaching tray was fabricated and carefully positioned over the bleaching agent during the session. The color was recorded at a baseline, 7 and 28 days after the bleaching session, using Vita Easy Shade spectrophotometer. Tooth sensitivity was recorded during (20 and 40 min) and immediately after the treatment using a visual analogue scale. The bleaching efficacy was evaluated by repeated-measures ANOVA, while the absolute risk of tooth sensitivity and its intensity were evaluated by Fisher's exact and Mann-Whitney tests, respectively (α=0.05). No significant difference on bleaching efficacy was observed between the conventional (7.4 and 8.1 ΔE) and sealed techniques (7.8 and 8.3 ΔE) at both evaluation periods. No significant difference was observed regarding the absolute risk of tooth sensitivity (p=0.15). Sealed technique showed a significant decrease of sensitivity intensity after 40 min (p=0.03). Sealed bleaching technique was able to reduce the sensitivity intensity during the bleaching procedure, without jeopardizing the bleaching efficacy

Estimating variation in field crew estimates of site index

1996 ◽  
Vol 26 (4) ◽  
pp. 560-565 ◽  
Author(s):  
Ronald E. McRoberts
Keyword(s):  
Repeated Measures ◽  
Site Index ◽  
Mixed Effects ◽  
Nonlinear Mixed Effects ◽  
Red Maple ◽  
Height Measurement ◽  
Nonlinear Mixed Effects Modeling ◽  
Mixed Effects Modeling ◽  
Residual Variation ◽  
Index Curve

Variances of red maple (Acerrubrum L.) and yellow birch (Betulaalleghaniensis Britt.) site index estimates were determined using nonlinear mixed effects modeling procedures and simulations. Site index curves for each species were constructed using repeated height–age observations for individual trees and plot site index estimates. Plot site index was calculated by linearly interpolating between the height observations corresponding to age observations bracketing the index age for each tree and then averaging over trees. Nonlinear mixed effects modeling procedures were used to estimate the parameters of the site index curve model because of the longitudinal, repeated-measures nature of the height–age data. Plot site index variances were determined by simulating the procedure used by Forest Inventory and Analysis field crews of the USDA Forest Service North Central Forest Experiment Station. At least three site index trees per plot were necessary to consistently obtain 95% confidence intervals whose widths were within ±20% of means. Variation among site index trees, residual variation around estimated height–age curves, and errors in height measurement were the greatest contributors to variation in plot site index estimates. Because the effects of these sources of variation cannot be readily reduced, it is unlikely that the variances of site index estimates can be reduced.

Music stimuli in mindfulness meditation: Comparison of musician and non-musician responses

2020 ◽  
pp. 030573562090133
Author(s):  
Eugenia Hernandez-Ruiz ◽  
Abbey L Dvorak ◽  
Kevin Weingarten
Keyword(s):  
Repeated Measures ◽  
Mindfulness Meditation ◽  
Mixed Effects ◽  
Analysis Of Covariance ◽  
Auditory Stimuli ◽  
Clinical Implications ◽  
Music Intervention ◽  
Group Status ◽  
Repeated Measures Design ◽  
Repeated Measures Analysis

The purpose of this study was to compare the effectiveness of and preference for different auditory stimuli on mindfulness meditation in musicians. A second purpose was to compare musician responses with non-musician responses from a previous study. A repeated-measures design exposed participants to four auditory stimuli of increased complexity. Participants ( N = 49) were undergraduate musicians with limited mindfulness experience. Data included absorption in music, mindfulness, and preference and usefulness of auditory stimuli. A repeated-measures analysis of covariance, with absorption of music as a covariate, found no significant differences between stimuli on mindfulness meditation according to musicians. Friedman’s analyses of variance indicated that musician rankings of usefulness and preference were significantly different among conditions. Both musicians and non-musicians ranked Melody and Harmony conditions as most preferred and most useful for mindfulness meditation. A mixed effects model with both groups indicated not only a significant effect of auditory stimuli on mindfulness but also interaction due to group status. A significant result was only obtained when the covariate was not considered. Absorption in music scores between groups was significantly higher for musicians than non-musicians. These outcomes support the hypothesis that absorption in music and music expertise may mediate the effect of a music intervention. Clinical implications are discussed.

scholarly journals Computerized Symbol Digit Modalities Test in a Swiss Pediatric Cohort – Part 2: Clinical Implementation

2021 ◽  
Vol 12 ◽  
Author(s):  
Marie-Noëlle Klein ◽  
Ursina Jufer-Riedi ◽  
Sarah Rieder ◽  
Céline Hochstrasser ◽  
Michelle Steiner ◽  
...  
Keyword(s):  
Test Performance ◽  
Repeated Measures ◽  
Analysis Of Covariance ◽  
Fine Motor ◽  
Clinical Implementation ◽  
Information Processing Speed ◽  
Repeated Measures Anova ◽  
Repeated Measures Analysis ◽  
Significant Difference ◽  
Motor Dexterity

BackgroundInformation processing speed (IPS) is a marker for cognitive function. It is associated with neural maturation and increases during development. Traditionally, IPS is measured using paper and pencil tasks requiring fine motor skills. Such skills are often impaired in patients with neurological conditions. Therefore, an alternative that does not need motor dexterity is desirable. One option is the computerized symbol digit modalities test (c-SDMT), which requires the patient to verbally associate numbers with symbols.MethodsEighty-six participants (8–16 years old; 45 male; 48 inpatients) were examined, 38 healthy and 48 hospitalized for a non-neurological disease. All participants performed the written SDMT, c-SDMT, and the Test of Non-verbal Intelligence Fourth Edition (TONI-4). Statistical analyses included a multivariate analysis of covariance (MANCOVA) for the effects of intelligence (IQ) and hospitalization on the performance of the SDMT and c-SDMT. A repeated measures analysis of variance (repeated measures ANOVA) was used to compare performance across c-SDMT trials between inpatients and outpatients.ResultsThe MANCOVA showed that hospitalization had a significant effect on IPS when measured with the SDMT (p = 0.04) but not with the c-SDMT (p = 0.68), while IQ (p = 0.92) had no effect on IPS. Age (p < 0.001) was the best predictor of performance of both tests. The repeated measures ANOVA revealed no significant difference in within-test performance (p = 0.06) between outpatient and inpatient participants in the c-SDMT.ConclusionPerformance of the c-SDMT is not confounded by hospitalization and gives within-test information. As a valid and reliable measure of IPS for children and adolescents, it is suitable for use in both inpatient and outpatient populations.

Self-Stigma Reduction Group for People With Depression: A Randomized Controlled Trial

2020 ◽  
Vol 30 (8) ◽  
pp. 846-857
Author(s):  
Daniel K. W. Young ◽  
Petrus Y. N. Ng ◽  
Patrick Corrigan ◽  
Renee Chiu ◽  
Shuyan Yang
Keyword(s):  
Randomized Controlled Trial ◽  
Depressive Symptoms ◽  
Repeated Measures ◽  
Controlled Trial ◽  
Clinical Depression ◽  
Assessment Tools ◽  
Analysis Of Covariance ◽  
Control Group ◽  
Chinese Society ◽  
Randomized Controlled

Purpose: This study aimed to evaluate the effectiveness of cognitive behavior therapy (CBT) on reducing self-stigma in Chinese people with depression. Methods: By adopting a randomized controlled trial design, 62 participants with clinical depression were randomly assigned to a 10-session CBT or treatment as usual. Standardized assessment tools were used to assess the self-stigma and depressive symptoms in the pre- and posttreatment periods by a research assistant who was blind to the group assignment of the participants. Results: The results of the 2 × 2 repeated measures of covariance (analysis of covariance) demonstrated that after completing the therapy, the treatment group had significantly lower self-stigma scores than the control group. Additionally, the reduction in self-stigmatizing beliefs predicted a reduction in depressive symptoms in participants. Conclusion: This study demonstrates the efficacy and effectiveness of a CBT group intervention in reducing self-stigma for people with clinical depression living in Chinese society.

One Size Fits All?

Methodology ◽  
2012 ◽  
Vol 8 (1) ◽  
pp. 23-38 ◽  
Author(s):  
Manuel C. Voelkle ◽  
Patrick E. McKnight
Keyword(s):  
Repeated Measures ◽  
Structural Equation ◽  
Type I Error ◽  
Equation Modeling ◽  
Type I ◽  
Finite Sample ◽  
Traditional Methods ◽  
Repeated Measures Anova ◽  
Special Cases ◽  
Latent Curve

The use of latent curve models (LCMs) has increased almost exponentially during the last decade. Oftentimes, researchers regard LCM as a “new” method to analyze change with little attention paid to the fact that the technique was originally introduced as an “alternative to standard repeated measures ANOVA and first-order auto-regressive methods” (Meredith & Tisak, 1990, p. 107). In the first part of the paper, this close relationship is reviewed, and it is demonstrated how “traditional” methods, such as the repeated measures ANOVA, and MANOVA, can be formulated as LCMs. Given that latent curve modeling is essentially a large-sample technique, compared to “traditional” finite-sample approaches, the second part of the paper addresses the question to what degree the more flexible LCMs can actually replace some of the older tests by means of a Monte-Carlo simulation. In addition, a structural equation modeling alternative to Mauchly’s (1940) test of sphericity is explored. Although “traditional” methods may be expressed as special cases of more general LCMs, we found the equivalence holds only asymptotically. For practical purposes, however, no approach always outperformed the other alternatives in terms of power and type I error, so the best method to be used depends on the situation. We provide detailed recommendations of when to use which method.

Extremism Leads to Ostracism

2020 ◽  
Vol 51 (3) ◽  
pp. 149-156
Author(s):  
Andrew H. Hales ◽  
Kipling D. Williams
Keyword(s):  
Mixed Effects ◽  
Social Connection ◽  
Mixed Effects Modeling ◽  
Activist Groups

Abstract. Ostracism has been shown to increase openness to extreme ideologies and groups. We investigated the consequences of this openness-to-extremity from the perspective of potential ostracizers. Does openness-to-extremity increase one’s prospects of being ostracized by others who are not affiliated with the extreme group? Participants rated willingness to ostracize 40 targets who belong to activist groups that vary in the type of goals/cause they support (prosocial vs. antisocial), and the extremity of their actions (moderate vs. extreme). Mixed-effects modeling showed that people are more willing to ostracize targets whose group engages in extreme actions. This effect was unexpectedly stronger for groups pursuing prosocial causes. It appears openness-to-extremity entails interpersonal cost, and could increase reliance on the extreme group for social connection.

scholarly journals Effectiveness of Abdominal and Gluteus Medius Training in Lumbo-Pelvic Stability and Adductor Strength in Female Soccer Players. A Randomized Controlled Study

2021 ◽  
Vol 18 (4) ◽  
pp. 1528
Author(s):  
Héctor Guerrero-Tapia ◽  
Rodrigo Martín-Baeza ◽  
Rubén Cuesta-Barriuso
Keyword(s):  
Repeated Measures ◽  
Gluteus Medius ◽  
Soccer Players ◽  
Controlled Study ◽  
Control Group ◽  
Extrinsic Factors ◽  
Randomized Controlled ◽  
Limb Injuries ◽  
Experimental Group

Background. Abdominal and lumbo-pelvic stability alterations may be the origin of lower limb injuries, such as adductor pathology in soccer players. Imbalance can be caused by both intrinsic and extrinsic factors. Methods: In this randomized controlled trial over 8 weeks, 25 female footballers were randomly allocated to an experimental group (isometric abdominal training and gluteus medius-specific training) or a control group (isometric abdominal training). Evaluations were performed at baseline, at the end of the intervention and after a 4-week follow-up period. The exercise protocol in common for both groups included three exercises: Plank, Lateral plank and Bird dog. Specific exercises for the gluteus medius were: Pelvic drop and Stabilization of the gluteus medius in knee valgus. Outcome measures were lumbar-pelvic stability and adductor strength. Results: After the intervention, there was an increase in lumbo-pelvic stability in both groups, being greater in the control group than in the experimental group (mean differences [MD]: 4.84 vs. MD: 9.58; p < 0.01) with differences in the analysis of repeated measures (p < 0.001), but not in group interaction (p = 0.26). Changes were found in adductor strength in the experimental group (MD: −2.48; p < 0.001 in the left adductor; MD: −1.48; p < 0.01 in right adductor) and control group (MD: −1.68; p < 0.001 in the left adductor; MD: −2.05; p < 0.001 in the right adductor) after the intervention, with differences in the analysis of repeated measures in left (p < 0.001) and right (p < 0.001) adductor strength. Conclusions: An abdominal and gluteal training protocol shows no advantage over a protocol of abdominal training alone for lumbo-pelvic stability and adductor strength, while improvements in both variables are maintained at four weeks follow-up.

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