scholarly journals A Comparison of Logistic Regression Models for DIF Detection in Polytomous Items: The Effect of Small Sample Sizes and Non-Normality of Ability Distributions

2016 ◽  
Vol 2 (1) ◽  
pp. 22-39 ◽  
Author(s):  
Yasemin KAYA ◽  
Walter L. Leite ◽  
M. David Miller
Keyword(s):  
Logistic Regression ◽  
Regression Models ◽  
Small Sample ◽  
Sample Sizes ◽  
Polytomous Items ◽  
Logistic Regression Models ◽  
Small Sample Sizes

Substantial effective sample sizes were required for external validation studies of predictive logistic regression models

2005 ◽  
Vol 58 (5) ◽  
pp. 475-483 ◽  
Author(s):  
Yvonne Vergouwe ◽  
Ewout W. Steyerberg ◽  
Marinus J.C. Eijkemans ◽  
J. Dik F. Habbema
Keyword(s):  
Logistic Regression ◽  
Validation Studies ◽  
Regression Models ◽  
External Validation ◽  
Sample Sizes ◽  
Logistic Regression Models

scholarly journals Topology and Geometry for Small Sample Sizes: An Application to Research on the Profoundly Gifted

2018 ◽  
Author(s):  
Colleen Molloy Farrelly
Keyword(s):  
Machine Learning ◽  
Logistic Regression ◽  
School Attendance ◽  
Gifted Students ◽  
Small Sample ◽  
Topological Data Analysis ◽  
Small Samples ◽  
Logistic Regression Models ◽  
Regression Methods ◽  
Small Sample Sizes

This study aims to confirm prior findings on the usefulness of topological data analysis (TDA) in the analysis of small samples, particularly focused on cohorts of profoundly gifted students, as well as explore the use of TDA-based regression methods for statistical modeling with small samples. A subset of the Gross sample is analyzed through supervised and unsupervised methods, including 16 and 17 individuals, respectively. Unsupervised learning confirmed prior results suggesting that evenly gifted and unevenly gifted subpopulations fundamentally differ. Supervised learning focused on predicting graduate school attendance and awards earned during undergraduate studies, and TDA-based logistic regression models were compared with more traditional machine learning models for logistic regression. Results suggest 1) that TDA-based methods are capable of handing small samples and seem more robust to the issues that arise in small samples than other machine learning methods and 2) that early childhood achievement scores and several factors related to childhood education interventions (such as early entry and radical acceleration) play a role in predicting key educational and professional achievements in adulthood. Possible new directions from this work include the use of TDA-based tools in the analysis of rare cohorts thus-far relegated to qualitative analytics or case studies, as well as potential exploration of early educational factors and adult-level achievement in larger populations of the profoundly gifted, particularly within the Study of Exceptional Talent and Talent Identification Program cohorts.

No Evidence that Experiencing Physical Warmth Promotes Interpersonal Warmth: Two Failures to Replicate Williams and Bargh (2008)

2018 ◽  
Author(s):  
Christopher Chabris ◽  
Patrick Ryan Heck ◽  
Jaclyn Mandart ◽  
Daniel Jacob Benjamin ◽  
Daniel J. Simons
Keyword(s):  
Null Hypothesis ◽  
Small Sample ◽  
Sample Sizes ◽  
Double Blind ◽  
Bayesian Analyses ◽  
Physical Warmth ◽  
Small Sample Sizes ◽  
Interpersonal Warmth

Williams and Bargh (2008) reported that holding a hot cup of coffee caused participants to judge a person’s personality as warmer, and that holding a therapeutic heat pad caused participants to choose rewards for other people rather than for themselves. These experiments featured large effects (r = .28 and .31), small sample sizes (41 and 53 participants), and barely statistically significant results. We attempted to replicate both experiments in field settings with more than triple the sample sizes (128 and 177) and double-blind procedures, but found near-zero effects (r = –.03 and .02). In both cases, Bayesian analyses suggest there is substantially more evidence for the null hypothesis of no effect than for the original physical warmth priming hypothesis.

The impact of SPY angiography on intraoperative decision making and outcomes for post-mastectomy reconstruction

2019 ◽  
pp. 1-5
Keyword(s):  
Decision Making ◽  
Logistic Regression ◽  
Skin Necrosis ◽  
Regression Models ◽  
Multivariable Analysis ◽  
P Value ◽  
Flap Necrosis ◽  
Single Institution ◽  
Logistic Regression Models ◽  
The Impact

Objective: While the use of intraoperative laser angiography (SPY) is increasing in mastectomy patients, its impact in the operating room to change the type of reconstruction performed has not been well described. The purpose of this study is to investigate whether SPY angiography influences post-mastectomy reconstruction decisions and outcomes. Methods and materials: A retrospective analysis of mastectomy patients with reconstruction at a single institution was performed from 2015-2017.All patients underwent intraoperative SPY after mastectomy but prior to reconstruction. SPY results were defined as ‘good’, ‘questionable’, ‘bad’, or ‘had skin excised’. Complications within 60 days of surgery were compared between those whose SPY results did not change the type of reconstruction done versus those who did. Preoperative and intraoperative variables were entered into multivariable logistic regression models if significant at the univariate level. A p-value <0.05 was considered significant. Results: 267 mastectomies were identified, 42 underwent a change in the type of planned reconstruction due to intraoperative SPY results. Of the 42 breasts that underwent a change in reconstruction, 6 had a ‘good’ SPY result, 10 ‘questionable’, 25 ‘bad’, and 2 ‘had areas excised’ (p<0.01). After multivariable analysis, predictors of skin necrosis included patients with ‘questionable’ SPY results (p<0.01, OR: 8.1, 95%CI: 2.06 – 32.2) and smokers (p<0.01, OR:5.7, 95%CI: 1.5 – 21.2). Predictors of any complication included a change in reconstruction (p<0.05, OR:4.5, 95%CI: 1.4-14.9) and ‘questionable’ SPY result (p<0.01, OR: 4.4, 95%CI: 1.6-14.9). Conclusion: SPY angiography results strongly influence intraoperative surgical decisions regarding the type of reconstruction performed. Patients most at risk for flap necrosis and complication post-mastectomy are those with questionable SPY results.

scholarly journals Effect of prostatic apex shape (Lee types) and urethral sphincter length in preoperative MRI on very early continence rates after radical prostatectomy

2021 ◽  
Author(s):  
Mike Wenzel ◽  
Felix Preisser ◽  
Matthias Mueller ◽  
Lena H. Theissen ◽  
Maria N. Welte ◽  
...  
Keyword(s):  
Logistic Regression ◽  
Radical Prostatectomy ◽  
Regression Models ◽  
Urethral Sphincter ◽  
Anatomical Characteristics ◽  
Logistic Regression Models ◽  
Pad Test ◽  
Type D ◽  
Multivariable Logistic Regression ◽  
Type C

Abstract Purpose To test the effect of anatomic variants of the prostatic apex overlapping the membranous urethra (Lee type classification), as well as median urethral sphincter length (USL) in preoperative multiparametric magnetic resonance imaging (mpMRI) on the very early continence in open (ORP) and robotic-assisted radical prostatectomy (RARP) patients. Methods In 128 consecutive patients (01/2018–12/2019), USL and the prostatic apex classified according to Lee types A–D in mpMRI prior to ORP or RARP were retrospectively analyzed. Uni- and multivariable logistic regression models were used to identify anatomic characteristics for very early continence rates, defined as urine loss of ≤ 1 g in the PAD-test. Results Of 128 patients with mpMRI prior to surgery, 76 (59.4%) underwent RARP vs. 52 (40.6%) ORP. In total, median USL was 15, 15 and 10 mm in the sagittal, coronal and axial dimensions. After stratification according to very early continence in the PAD-test (≤ 1 g vs. > 1 g), continent patients had significantly more frequently Lee type D (71.4 vs. 54.4%) and C (14.3 vs. 7.6%, p = 0.03). In multivariable logistic regression models, the sagittal median USL (odds ratio [OR] 1.03) and Lee type C (OR: 7.0) and D (OR: 4.9) were independent predictors for achieving very early continence in the PAD-test. Conclusion Patients’ individual anatomical characteristics in mpMRI prior to radical prostatectomy can be used to predict very early continence. Lee type C and D suggest being the most favorable anatomical characteristics. Moreover, longer sagittal median USL in mpMRI seems to improve very early continence rates.

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