Do We Relatively or Absolutely Overestimate Rare Events?

2014 ◽  
Vol 73 (4) ◽  
pp. 193-204
Author(s):  
Aileen Oeberst ◽  
Susanne Haberstroh
Keyword(s):  
Rare Events ◽  
Rare Event ◽  
Small Sample ◽  
Regression To The Mean ◽  
Outcome Valence ◽  
Frequency Judgments ◽  
Psychology Literature ◽  
Small Sample Sizes ◽  
Distinct Features ◽  
The Impact

How good are we at estimating the frequency of rare events? Previous evidence has been mixed: While some studies report well-calibrated frequency judgments, others found rare events to be overestimated. We examined whether the distinctiveness of a rare event fosters overestimation. Distinctiveness may result from exceptional valence, statistical infrequency, or the joint occurrence of two distinct features. Such paired distinctiveness has been found to be particularly salient. We conducted two experiments to investigate the impact of paired distinctiveness and valence on frequency estimations of rare events by combining two paradigms from the decision-making literature and the social psychology literature on stereotypes. The results indicate that rarity alone does not necessarily result in overestimation; rather, the combination of statistical infrequency and small sample sizes (i.e., paired distinctiveness) led participants to overestimate the frequency of a rare event. We were able to rule out alternative explanations such as regression to the mean, but the exact role of outcome valence needs further investigation.

scholarly journals Viscoelastometric Testing to Assess Hemostasis of COVID-19: A Systematic Review

2021 ◽  
Vol 10 (8) ◽  
pp. 1740
Author(s):  
Marion Bareille ◽  
Michaël Hardy ◽  
Jonathan Douxfils ◽  
Stéphanie Roullet ◽  
Dominique Lasne ◽  
...  
Keyword(s):  
Systematic Review ◽  
Mechanical Strength ◽  
Small Sample ◽  
The Common ◽  
Small Sample Sizes ◽  
Definition Of ◽  
Reported Data ◽  
Prophylactic Anticoagulation ◽  
The Impact ◽  
Heparin Neutralization

Infection by SARS-CoV-2 is associated with a high risk of thrombosis. The laboratory documentation of hypercoagulability and impaired fibrinolysis remains a challenge. Our aim was to assess the potential usefulness of viscoelastometric testing (VET) to predict thrombotic events in COVID-19 patients according to the literature. We also (i) analyzed the impact of anticoagulation and the methods used to neutralize heparin, (ii) analyzed whether maximal clot mechanical strength brings more information than Clauss fibrinogen, and (iii) critically scrutinized the diagnosis of hypofibrinolysis. We performed a systematic search in PubMed and Scopus databases until December 31st, 2020. VET methods and parameters, and patients’ features and outcomes were extracted. VET was performed for 1063 patients (893 intensive care unit (ICU) and 170 non-ICU, 44 studies). There was extensive heterogeneity concerning study design, VET device used (ROTEM, TEG, Quantra and ClotPro) and reagents (with non-systematic use of heparin neutralization), timing of assay, and definition of hypercoagulable state. Notably, only 4 out of 25 studies using ROTEM reported data with heparinase (HEPTEM). The common findings were increased clot mechanical strength mainly due to excessive fibrinogen component and impaired to absent fibrinolysis, more conspicuous in the presence of an added plasminogen activator. Only 4 studies out of the 16 that addressed the point found an association of VETs with thrombotic events. So-called functional fibrinogen assessed by VETs showed a variable correlation with Clauss fibrinogen. Abnormal VET pattern, often evidenced despite standard prophylactic anticoagulation, tended to normalize after increased dosing. VET studies reported heterogeneity, and small sample sizes do not support an association between the poorly defined prothrombotic phenotype of COVID-19 and thrombotic events.

scholarly journals Cannabis and breastfeeding

2020 ◽  
Vol 25 (Supplement_1) ◽  
pp. S26-S28 ◽  
Author(s):  
Lisa Graves
Keyword(s):  
Health Care Providers ◽  
Small Sample ◽  
Adverse Outcomes ◽  
Care Providers ◽  
High Quality ◽  
High Quality Evidence ◽  
Small Sample Sizes ◽  
The Impact ◽  
Quality Evidence

Abstract Cannabis is one of the most commonly used substances in Canada with 15% of Canadians reporting use in 2019. There is emerging evidence that cannabis is linked to an impact on the developing brain in utero and adverse outcomes in infants, children, and adolescents. The impact of cannabis during breastfeeding has been limited by studies with small sample sizes, follow-up limited to 1 year and the challenge of separating prenatal exposure from that during breastfeeding. In the absence of high-quality evidence, health care providers need to continue to engage women in conversation about the potential concerns related to breastfeeding and cannabis use.

Real-world data evaluating immunotherapy markers and checkpoint inhibitor response among GI cancers in a large community-based oncology network.

2021 ◽  
Vol 39 (3_suppl) ◽  
pp. 113-113
Author(s):  
Carissa Jones ◽  
Rebecca Lachs ◽  
Emma Sturgill ◽  
Amanda Misch ◽  
Caressa Lietman ◽  
...  
Keyword(s):  
Checkpoint Inhibitor ◽  
Small Sample ◽  
Tumor Type ◽  
Real World Data ◽  
Loss To Follow Up ◽  
Kaplan Meier ◽  
Gi Cancers ◽  
Small Sample Sizes ◽  
Line Of Therapy ◽  
The Impact

113 Background: Checkpoint inhibitor (CPI) therapies have shown prolonged survival in patients (pts) with microsatellite instability (MSI). Tumor mutation burden (TMB) has also been associated with benefit from CPIs, with pembrolizumab recently approved for solid tumors with a TMB of ≥10 muts/mb. However, the validity of a tissue-agnostic approach has been debated given the high degree of TMB variation across tumor types. We sought to evaluate the impact of TMB and MSI on CPI response in pts with advanced gastrointestinal (GI) cancers who received NGS profiling. Methods: Patients within the Sarah Cannon network with GI cancer and comprehensive next generation sequencing (NGS) data were identified through Genospace, Sarah Cannon’s clinico-genomic analytics platform. Microsatellite (MS) status [high (MSI-H) vs. stable (MSS)] was defined by NGS. TMB-high (TMB-H) was defined as ≥10 muts/mb. Kaplan-Meier estimates were used to examine time to treatment failure (TTF), defined as the time from therapy start to start of next therapy, death, or loss to follow-up. Results: We identified 5,788 pts with GI cancers who received NGS, of which 48% (N=3,603) had colorectal cancer (CRC). MS status was evaluated on 4,219 (66%) NGS reports, TMB on 2,922 (46%) reports, and both on 2,863 (45%) reports. MSI-H and TMB-H co-occurred on 127 reports (4%), MSS/TMB-H occurred on 312 reports (11%), and MSS/TMB-Low (TMB-L) occurred on 2,424 reports (85%). No reports were MSI-H/TMB-L. Overall, 580 pts (14%) received CPI therapy (N=52 MSI-H/TMB-H, N=41 MSS/TMB-H, N=215 MSS/TMB-L). Independent of line of therapy or tumor type, TTF was significantly shorter for CPI vs. non-CPI therapies [median TTF (mTTF)=151 vs. 238 days, respectively, p=3.4x10-9]. As expected, MSI-H was also associated with longer CPI TTF compared to MSS (mTTF=727 vs. 124 days, p=3.1x10-11). Due to small sample sizes, further analyses were focused on pts with CRC (Table). TMB-H was independently associated with longer CPI TTF compared to TMB-L (Table, p=9.2x10-10). Similarly, the co-occurrence of MSI-H/TMB-H was also associated with longer CPI TTF (Table). However, there was no difference in CPI TTF for MSS/TMB-H and MSS/TMB-L (Table, p=0.45). All pts who received non-CPI therapies, regardless of MS/TMB group, had longer TTF than MSS/TMB-H and MSS/TMB-L pts who received CPI (Table). mTTF [days (N)] for pts with CRC by biomarker. Conclusions: Despite recent tissue-agnostic approvals, TMB does not appear to be a good biomarker of CPI response in pts with CRC. Rather, time to CPI failure is associated with the co-occurrence of TMB-H with MSI-H. Continued research is needed to identify better biomarkers of response to immunotherapy in GI cancers. [Table: see text]

scholarly journals The impact of the 30 most cited articles on hip arthroscopy: what is the subject matter?

2020 ◽  
Vol 7 (1) ◽  
pp. 14-21
Author(s):  
Alexander von Glinski ◽  
Emre Yilmaz ◽  
Ryan Goodmanson ◽  
Clifford Pierre ◽  
Sven Frieler ◽  
...  
Keyword(s):  
Surgical Treatment ◽  
Hip Arthroscopy ◽  
Randomized Clinical Trials ◽  
Technical Note ◽  
Small Sample ◽  
Level Of Evidence ◽  
Thomson Reuters ◽  
Treatment Indications ◽  
Small Sample Sizes ◽  
The Impact

Abstract The purpose of this study was to identify the 30 most cited articles on hip arthroscopy and discuss their influence on recent surgical treatment. Due to advancements in hip arthroscopy, there is a widening spectrum of diagnostic and treatment indications. The purpose of this study was to identify the 30 most cited articles on hip arthroscopy and discuss their influence on contemporary surgical treatment. The Thomson Reuters Web of Science was used to identify the 30 most cited studies on hip arthroscopy between 1900 and 2018. These 30 articles generated 6152 citations with an average of 205.07 citations per item. Number of citations ranged from 146 to 461. Twenty-five out of the 30 papers were clinical cohort studies with a level of evidence between III and IV, encompassing 4348 patients. Four studies were reviewed (one including a technical note) and one a case report. We were able to identify the 30 most cited articles in the field of hip arthroscopy. Most articles were reported in high-impact journals, but reported small sample sizes in a retrospective setting. Prospective multi-arm cohort trials or randomized clinical trials represent opportunities for future studies.

The scale of it all: postcanine tooth size, the taxon-level effect, and the universality of Gould's scaling law

Paleobiology ◽  
2010 ◽  
Vol 36 (2) ◽  
pp. 188-203 ◽  
Author(s):  
Lynn E. Copes ◽  
Gary T. Schwartz
Keyword(s):  
Body Mass ◽  
Scaling Law ◽  
Small Sample ◽  
Tooth Size ◽  
Mathematical Methods ◽  
Scaling Relationship ◽  
Small Sample Sizes ◽  
Relationship Of ◽  
The Impact ◽  
Level Effect

In a seminal paper in 1975, Gould proposed that postcanine occlusal area (PCOA) should scale metabolically (0.75) with body mass across mammals. By regressing PCOA against skull length in a small sample of large-bodied herbivorous mammals, Gould provided some marginal support for this hypothesis, which he then extrapolated as a universal scaling law for Mammalia. Since then, many studies have sought to confirm this scaling relationship within a single order and have found equivocal support for Gould's assertion. In part, this may be related to the use of proxies for both PCOA and body mass, small sample sizes, or the influence of a “taxon-level effect,” rendering Gould's scaling “universal” problematic.Our goal was to test the universality of Gould's prediction and the impact of the taxon-level effect on regressions of tooth size on body mass in a large extant mammalian sample (683 species spanning 14 orders). We tested for the presence of two types of taxon-level effect that may influence the acceptance or rejection of hypothesized scaling coefficients. The hypotheses of both metabolic and isometric scaling can be rejected in Mammalia, but not in all sub-groups therein. The level of data aggregation also influences the interpretation of the scaling relationship. Because the scaling relationship of tooth size to body mass is highly dependent on both the taxonomic level of analysis and the mathematical methods used to organize the data, paleontologists attempting to retrodict body mass from fossilized dental remains must be aware of the effect that sample composition may have on their results.

scholarly journals Integrating multi-omics data with deep learning for predicting cancer prognosis

2019 ◽  
Author(s):  
Hua Chai ◽  
Xiang Zhou ◽  
Zifeng Cui ◽  
Jiahua Rao ◽  
Zheng Hu ◽  
...  
Keyword(s):  
Deep Learning ◽  
Proportional Hazards ◽  
Proportional Hazards Model ◽  
Small Sample ◽  
The Cancer Genome Atlas ◽  
Cancer Prognosis ◽  
Omics Data ◽  
Hazards Model ◽  
Small Sample Sizes ◽  
The Impact

AbstractMotivationAccurately predicting cancer prognosis is necessary to choose precise strategies of treatment for patients. One of effective approaches in the prediction is the integration of multi-omics data, which reduces the impact of noise within single omics data. However, integrating multi-omics data brings large number of redundant variables and relative small sample sizes. In this study, we employed Autoencoder networks to extract important features that were then input to the proportional hazards model to predict the cancer prognosis.ResultsThe method was applied to 12 common cancers from the Cancer Genome Atlas. The results show that the multi-omics averagely improves 4.1% C-index for prognosis prediction over single mRNA data, and our method outperforms previous approaches by at least 7.4%. A comparison of the contribution of single omics data show that mRNA contributes the most, followed by the DNA methylation, miRNA, and the copy number variation. In the case study for differential gene expression analysis, we identified 161 differentially expressed genes in the cervical cancer, among which 77 genes (65.8%) have been proven to be associated with cancer. In addition, we performed the cross-cancer test where the model trained on one cancer was used to predict the prognosis of another cancer, and found 23 pairs of cancers have a C-index larger than 0.5, with the largest value of 0.68. Thus, this study has provided a deep learning framework to effectively integrate multiple omics data to predict cancer prognosis.

scholarly journals Logistic Regression Under Sparse Data Conditions

2020 ◽  
Vol 18 (2) ◽  
pp. 2-18
Author(s):  
David A. Walker ◽  
Thomas J. Smith
Keyword(s):  
Logistic Regression ◽  
Parameter Estimation ◽  
Sparse Data ◽  
Small Sample ◽  
Potential Parameter ◽  
Predictor Variables ◽  
Estimation Bias ◽  
Small Sample Sizes ◽  
The Impact ◽  
Reducing Potential

The impact of sparse data conditions was examined among one or more predictor variables in logistic regression and assessed the effectiveness of the Firth (1993) procedure in reducing potential parameter estimation bias. Results indicated sparseness in binary predictors introduces bias that is substantial with small sample sizes, and the Firth procedure can effectively correct this bias.

scholarly journals A Review of Telemedicine Interventions for Weight Loss

2021 ◽  
Vol 15 (9) ◽  
Author(s):  
Kelsey Ufholz ◽  
Daksh Bhargava
Keyword(s):  
Weight Loss ◽  
Digital Literacy ◽  
Small Sample ◽  
Text Messages ◽  
Treatment Access ◽  
Self Monitoring ◽  
Portion Control ◽  
Phone Calls ◽  
Small Sample Sizes ◽  
The Impact

Abstract Purpose of Review Telemedicine has become popular as an alternative for in-person weight loss treatment during the COVID-19 pandemic. This review focuses on weight loss interventions utilizing real-time telemedicine. Recent Findings Telemedicine interventions are usually run as a weekly counseling and educational session or as a complement to a primarily Web-based intervention. A wide variety of healthcare professionals may provide the intervention. Common content includes portion control, increased physical activity, and relapse prevention. Self-monitoring is associated with intervention success. Modalities considered include online chats, text messages, phone calls, and videoconferences. Videoconferencing may be especially useful in capturing the interpersonal connection associated with in-person care but is understudied compared to other modalities. While many interventions show improvements in weight and weight-related outcomes, small sample sizes limit generalizability. Technology access and digital literacy are both necessary. Summary Telemedicine interventions can successfully help patients with obesity lose weight. Telemedicine interventions provide a safe, remote alternative and may expand treatment access to hard-to-reach populations. Further research is needed on telemedicine weight loss treatments for seniors, men, and ethnic minorities, as well as on the impact of long-term interventions.

scholarly journals Neuroplasticity and Motor Rehabilitation in Multiple Sclerosis: A Systematic Review on MRI Markers of Functional and Structural Changes

2021 ◽  
Vol 15 ◽  
Author(s):  
Eleonora Tavazzi ◽  
Marta Cazzoli ◽  
Alice Pirastru ◽  
Valeria Blasi ◽  
Marco Rovaris ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Structural Changes ◽  
Diffusion Tensor ◽  
Structural Connectivity ◽  
Structural Mri ◽  
Resting State Fmri ◽  
Small Sample ◽  
Motor Rehabilitation ◽  
Small Sample Sizes ◽  
The Impact

Background: Motor rehabilitation is routinely used in clinical practice as an effective method to reduce progressive disability gain in multiple sclerosis (MS), but rehabilitation approaches are typically unstandardized, and only few studies have investigated the impact of rehabilitation on brain neuroplasticity.Objective: To summarize and critically analyze studies applying MRI markers of functional connectivity and structural changes to assess the effect of motor rehabilitation on brain neuroplasticity in MS.Methods: Literature search was performed using PubMed and EMBASE, selecting studies having as a subject motor rehabilitation and advanced MRI techniques investigating neuroplasticity in adult patients affected by MS.Results: Seventeen out of 798 papers were selected, of which 5 applied structural MRI (4 diffusion tensor imaging, 1 volumetric measurements), 7 applied functional fMRI (5 task-related fMRI, 2 resting-state fMRI) whereas the remaining 5 applied both structural and functional imaging.Discussion: The considerable data heterogeneity and the small sample sizes characterizing the studies limit interpretation and generalization of the results. Overall, motor rehabilitation promotes clinical improvement, paralleled by positive adaptive brain changes, whose features and extent depend upon different variables, including the type of rehabilitation approach. MRI markers of functional and structural connectivity should be implemented in studies testing the efficacy of motor rehabilitation. They allow for a better understanding of neuroplastic mechanisms underlying rehabilitation-mediated clinical achievements, facilitating the identification of rehabilitation strategies tailored to patients' needs and abilities.

scholarly journals What is the evidence for mirtazapine in treating cancer-related symptomatology? A systematic review

2019 ◽  
Vol 28 (4) ◽  
pp. 1597-1606 ◽  
Author(s):  
Guillaume Economos ◽  
Natasha Lovell ◽  
Anna Johnston ◽  
Irene J. Higginson
Keyword(s):  
Systematic Review ◽  
Small Sample Size ◽  
Poor Quality ◽  
Small Sample ◽  
Assessment Tools ◽  
Data Synthesis ◽  
Small Sample Sizes ◽  
Randomised Controlled ◽  
Multiple Symptoms ◽  
The Impact

Abstract Purpose Cancer patients often experience multiple distressing symptoms which are challenging to manage. It would therefore be helpful to find a treatment that alleviates more than one symptom, to avoid polypharmacy: mirtazapine has been used in several studies for this purpose. The objective of this study was to assess the effectiveness and safety of mirtazapine in alleviating one or more frequently encountered cancer-related symptoms. Methods Systematic review of clinical trials in English or French. Eight databases were searched. Included studies assessed the effectiveness of mirtazapine in alleviating one or more frequently encountered cancer-related symptoms. Comparator and validated assessment tools were required. Studies were independently appraised by two investigators before data synthesis. Results The search yielded 1898 references, from which we identified 12 relevant articles evaluating highly heterogeneous outcomes. These were two randomised-controlled (RCTs), three non-randomised controlled, and seven non-randomised non-controlled trials. In total, 392 participants were included and 185 were in RCTs. No study assessed the effectiveness of mirtazapine in alleviating symptoms at the same time, but some considered more than one symptom. Overall, the data was of poor quality, limited by small sample size and bias. However, mirtazapine showed effectiveness in treating depression, anxiety, sleep disorders, emesis and neuropathic pain. Across all studies, mirtazapine is safe to use, with drowsiness and dizziness the most common side-effects. Conclusion Study design and small sample sizes limit the ability to interpret results. Trials to assess the impact of mirtazapine or other medicines in alleviating multiple symptoms would be valuable.

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