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"Control Groups"
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Effects of a short period of postural training on postural stability and vestibulospinal reflexes
The effects of postural training on postural stability and vestibulospinal reflexes (VSRs) were investigated in normal subjects. A period (23 minutes) of repeated episodes (n = 10, 50 seconds) of unipedal stance elicited a progressive reduction of the area covered by centre of pressure (CoP) displacement, of average CoP displacement along the X and Y axes and of CoP velocity observed in this challenging postural task. All these changes were correlated to each other with the only exception of those in X and Y CoP displacement. Moreover, they were larger in the subjects showing higher initial instability in unipedal stance, suggesting that they were triggered by the modulation of sensory afferents signalling body sway. No changes in bipedal stance occurred soon and 1 hour after this period of postural training, while a reduction of CoP displacement was apparent after 24 hours, possibly due to a beneficial effect of overnight sleep on postural learning. The same period of postural training also reduced the CoP displacement elicited by electrical vestibular stimulation (EVS) along the X axis up to 24 hours following the training end. No significant changes in postural parameters of bipedal stance and VSRs could be observed in control experiments where subjects were tested at identical time points without performing the postural training. Therefore, postural training led to a stricter control of CoP displacement, possibly acting through the cerebellum by enhancing feedforward mechanisms of postural stability and by depressing the VSR, the most important reflex mechanism involved in balance maintenance under challenging conditions.
Journal Article
Fuzzy Differences-in-Differences
Difference-in-differences (DID) is a method to evaluate the effect of a treatment. In its basic version, a “control group” is untreated at two dates, whereas a “treatment group” becomes fully treated at the second date. However, in many applications of the DID method, the treatment rate only increases more in the treatment group. In such fuzzy designs, a popular estimator of the treatment effect is the DID of the outcome divided by the DID of the treatment. We show that this ratio identifies a local average treatment effect only if the effect of the treatment is stable over time, and if the effect of the treatment is the same in the treatment and in the control group. We then propose two alternative estimands that do not rely on any assumption on treatment effects, and that can be used when the treatment rate does not change over time in the control group. We prove that the corresponding estimators are asymptotically normal. Finally, we use our results to reassess the returns to schooling in Indonesia.
Journal Article
Exploring the Moderating Effect of Control Group Type on Intervention Effectiveness in School-Based Anxiety and Depression Prevention: Findings from a Rapid Review and Network Meta-analysis
Many randomized controlled trials have investigated the role of school-based prevention interventions to reduce symptoms of anxiety and depression in young people. Systematic reviews have subsequently demonstrated a small, beneficial effect of these interventions when compared to a combined control group including usual care, no intervention, or waiting list controls. However, evidence from behavioral science and clinical psychology suggests control group choice may influence the relative effectiveness of non-pharmacological interventions. Here we explored whether separating this combined control group into distinct categories might influence the apparent effectiveness of preventive interventions. After updating an earlier review and network meta-analysis of preventive interventions for anxiety and depression in young people, we considered the impact of alternative control groups on estimates of effectiveness. This analysis was restricted to comparisons with cognitive-behavioral interventions only—the most common intervention used in the included studies. In targeted populations, for both anxiety and depression outcomes, the effect of a cognitive-behavioral intervention was larger when compared to waiting list controls than to usual curriculum, no intervention, or attention controls. For anxiety, the effect of no intervention was also considerably larger than waiting list control (standardized mean difference -0.37 [95% credible interval − 0.66, − 0.11], favoring no intervention). These results suggest that the beneficial effect of preventive school-based interventions previously observed in standard meta-analyses may be an artifact of combining control groups. Although exploratory, these findings indicate the impact of different control groups may vary considerably and should be taken into account when interpreting the effectiveness of interventions.
Journal Article
Bilingualism with minority languages: Why searching for unicorn language users does not move us forward
This paper addresses several problematic scientific practices in psycholinguistic research. We discuss challenges that arise when working with minority languages, such as the notion of monolingual/monocultural normality and its historical origins, the stereotype of native-speakerism, the quest for testing people who fit specific profiles, the implications of the policy that urges scholars to match bilingual groups to monolingual comparison groups, and the use of powerful theoretical narratives that may evoke problematic labels and ableist terminology. These issues invest the field of psycholinguistics with questionable practices that contribute to the marginalization of groups that do not tick the standard normative boxes. Surveying some of the most widespread scientific practices in the field of psycholinguistics, our emphasis is on how several processes and policies may embody stereotypes that contribute to the exclusion of certain groups from the scientific literature, with grievous consequences for the visibility and the representation of some minoritized languages.
Journal Article
The effectiveness of psychological treatments for obsessive-compulsive disorders: a meta-analysis of randomized controlled trials published over last 30 years
Although numerous studies have examined the effects of psychological treatments for obsessive-compulsive disorder (OCD), their overall effectiveness remains unclear. We aimed to estimate their overall effect by combining all available randomized controlled trials (RCTs) comparing psychological treatments to control groups for OCD.
We conducted a meta-analysis of 48 RCTs with 55 comparisons published between 1992 and 1 January 2023. The primary outcome was OCD symptom severity, with Hedges' g calculated at post-treatment and follow-up. Random-effects models were employed for all analyses, and the risk of bias was assessed.
In general, psychological treatments demonstrated a significantly large effect (
= -1.14; 95% CI [-1.31 to -0.97];
= 72.23%) on reducing OCD symptom severity post-treatment, this finding remained consistent across measures and after excluding outliers, but lost significance in the sensitivity analysis for only studies with low risk of bias. Type of treatment, control group and treatment format were associated with treatment effects. Moreover, more severe baseline OCD symptom severity predicted higher degree of treatment efficacy. No significant differences were observed in dropout rates between the treatment and control groups. Treatment effects lost significance at 3-6 and 6-12 month follow-ups. 87% of RCTs were rated at high risk of bias.
Psychological treatments are effective in reducing OCD symptom severity. However, caution should be exercised when interpreting these results due to the high heterogeneity and risk of bias across RCTs. Future studies with more rigorous methodology are required, as well as studies examining their long-term effectiveness.
Journal Article
Analysis of rat toxicology studies: statistical agreement between virtual and concurrent controls in detecting treatment effects on liver enzymes
Virtual control groups (VCGs) are proposed as a means to reduce reliance on live animals in preclinical toxicology studies. Despite the potential benefits of VCGs, concerns remain regarding their comparability to traditional concurrent control groups (CCGs), and the risk of introducing bias into preclinical toxicology research. Our simulation focused on observing the statistical consequences of replacing the CCG (fully or partially) with VCGs derived from historical data, assessing their feasibility and limitations, and determining if VCG use alters study conclusions on selected toxicological endpoints.
We conducted simulations comparing liver enzyme activity in studies using VCGs and those using CCGs. VCGs were generated by simple matching using a limited set of criteria to a large-scale dataset. One hundred VCGs were generated for each reanalyzed study and the percentage of agreement with CCGs was then assessed across a variety of statistical measures for a selection of endpoints, i.e., liver enzymes and bodyweight.
Full agreement was observed in 46.9% of the performed comparisons between VCGs and CCGs, while full disagreement was noted in 2.6% of comparisons. For the remaining instances of partial agreement, the sampled VCGs predominantly aligned with the CCGs. Discrepancies observed did not consistently affect all measured endpoints within a given analyzed study; they were especially noted when CCG enzyme activity levels approached the boundaries of reference intervals, differing significantly from the majority of the other controls in the database. Partial replacement of CCG with VCG improved the overall agreement. The likelihood of reaching a different conclusion for the overall study outcome was considered to be low. Among the statistical methods used for comparing controls versus treated animals, the method based on the calculation of effect size appeared to be the most appropriate to use, especially with our resampling approach.
Our results suggest VCGs could be a potential alternative to CCGs. Key next steps that will need to be addressed include enhancing datasets with richer metadata and standardizing variables across studies to facilitate the selection of matching criteria, refining methods for managing outliers and hypothesis testing, and establishing proxy variables for animal growth.
Journal Article
A history of ankle sprain alters ankle coordination in both limbs during running
Context:Ankle sprain alters joint coordination, but its effect on the ankle coordination of the associated non-injured limbs during running remains unknown.Objective:The present study aimed to investigate the effects of a history of ankle sprain or chronic ankle sprain on the coordination in both involved and uninvolved limbs during running.Design:Cross-sectional studySetting:LaboratoryPatients or Other Participants:Seventeen individuals with chronic ankle instability (CAI), 17 copers and 17 controls ran at 2.68 m/s while 3D kinematics were collected. Main Outcome Measure (s):A vector coding technique was used to measure coupling of frontal plane ankle motion/transverse plane tibia motion (FAK/TT) and sagittal plane ankle motion/transverse plane tibia motion (SAK/TT) in both limbs. A curve analysis was performed to compare coupling angles between limbs within groups, and between the uninjured limbs of control and coper groups with the control group.Results:No differences in coupling were found between the injured and non-injured limbs in each group, or left and right limbs in the control group. Overall, controls had greater SAK/TT coupling angles than individuals with CAI, but there were no differences in SAK/TT coupling angles in copers compared to individuals with CAI and controls. Controls had greater FAK/TT coupling angles than copers, but there were no differences in FAK/TT coupling angles in individuals with CAI compared to copers and controls.Conclusions:All groups demonstrated that both limbs within an individual display the same patterns of ankle joint coupling. This finding implies that adaptation of the interlimb ankle coordination restored symmetry throughout the entire gait cycle of running following an ankle sprain
Journal Article
Variations in the Design and Use of Attention Control Groups in Type 2 Diabetes Randomized Controlled Trials: a Systematic Review
Purpose of ReviewIn type 2 diabetes (T2D) research, the phrase “attention control group” (ACGs) has been used with varying descriptions. We aimed to systematically review the variations in the design and use of ACGs for T2D studies.Recent FindingsTwenty studies utilizing ACGs were included in the final evaluation. Control group activities had the potential to influence the primary outcome of the study in 13 of the 20 articles. Prevention of contamination across groups was not mentioned in 45% of the articles. Eighty-five percent of articles met or somewhat met the criteria for having comparable activities between the ACG and intervention arms.SummaryWide variations in descriptions and the lack of standardization have led to an inaccurate use of the phrase “ACGs” when describing the control arm of trials, indicating a need for future research with focus on the adoption of uniform guidelines for use of ACGs in T2D RCTs.
Journal Article