scholarly journals Statistics for N = 1

2020 ◽  
Vol 30 (1) ◽  
pp. e38066
Author(s):  
Jimmie Leppink
Keyword(s):  
Statistical Approach ◽  
Small Samples ◽  
Outcome Variable ◽  
Interval Estimates ◽  
Linear Relations ◽  
Large Samples ◽  
Different Types ◽  
Research In Education ◽  
Study Designs ◽  
Larger Sample

Research in education is often associated with comparing group averages and linear relations in sufficiently large samples and evidence-based practice is about using the outcomes of that research in the practice of education. However, there are questions that are important for the practice of education that cannot really be addressed by comparisons of group averages and linear relations, no matter how large the samples. Besides, different types of constraints including logistic, financial, and ethical ones may make larger-sample research unfeasible or at least questionable. What has remained less known in many fields is that there are study designs and statistical methods for research involving small samples or even individuals that allow us to address questions of importance for the practice of education. This article discusses one type of such situations and provides a simple coherent statistical approach that provides point and interval estimates of differences of interest regardless of the type of the outcome variable and that is of use in other types of studies involving large samples, small samples, and single individuals.

How to Correct for Chance Agreement in the Estimation of Sensitivity and Specificity of Diagnostic Tests

1994 ◽  
Vol 33 (02) ◽  
pp. 180-186 ◽  
Author(s):  
H. Brenner ◽  
O. Gefeller
Keyword(s):  
Sensitivity And Specificity ◽  
Disease Status ◽  
Disease Prevalence ◽  
Small Sample ◽  
Small Samples ◽  
Interval Estimate ◽  
Traditional Concept ◽  
Interval Estimates ◽  
Major Disadvantage ◽  
Test Result

Abstract:The traditional concept of describing the validity of a diagnostic test neglects the presence of chance agreement between test result and true (disease) status. Sensitivity and specificity, as the fundamental measures of validity, can thus only be considered in conjunction with each other to provide an appropriate basis for the evaluation of the capacity of the test to discriminate truly diseased from truly undiseased subjects. In this paper, chance-corrected analogues of sensitivity and specificity are presented as supplemental measures of validity, which pay attention to the problem of chance agreement and offer the opportunity to be interpreted separately. While recent proposals of chance-correction techniques, suggested by several authors in this context, lead to measures which are dependent on disease prevalence, our method does not share this major disadvantage. We discuss the extension of the conventional ROC-curve approach to chance-corrected measures of sensitivity and specificity. Furthermore, point and asymptotic interval estimates of the parameters of interest are derived under different sampling frameworks for validation studies. The small sample behavior of the estimates is investigated in a simulation study, leading to a logarithmic modification of the interval estimate in order to hold the nominal confidence level for small samples.

scholarly journals ‘Statistical Irreproducibility’ Does Not Improve with Larger Sample Size: How to Quantify and Address Disease Data Multimodality in Human and Animal Research

2021 ◽  
Vol 11 (3) ◽  
pp. 234
Author(s):  
Abigail R. Basson ◽  
Fabio Cominelli ◽  
Alexander Rodriguez-Palacios
Keyword(s):  
Sample Size ◽  
Data Visualization ◽  
Random Sampling ◽  
Intestinal Inflammation ◽  
Random Number Generation ◽  
Outcome Data ◽  
Multimodal Distributions ◽  
Disease Subtypes ◽  
Study Designs ◽  
Larger Sample

Poor study reproducibility is a concern in translational research. As a solution, it is recommended to increase sample size (N), i.e., add more subjects to experiments. The goal of this study was to examine/visualize data multimodality (data with >1 data peak/mode) as cause of study irreproducibility. To emulate the repetition of studies and random sampling of study subjects, we first used various simulation methods of random number generation based on preclinical published disease outcome data from human gut microbiota-transplantation rodent studies (e.g., intestinal inflammation and univariate/continuous). We first used unimodal distributions (one-mode, Gaussian, and binomial) to generate random numbers. We showed that increasing N does not reproducibly identify statistical differences when group comparisons are repeatedly simulated. We then used multimodal distributions (>1-modes and Markov chain Monte Carlo methods of random sampling) to simulate similar multimodal datasets A and B (t-test-p = 0.95; N = 100,000), and confirmed that increasing N does not improve the ‘reproducibility of statistical results or direction of the effects’. Data visualization with violin plots of categorical random data simulations with five-integer categories/five-groups illustrated how multimodality leads to irreproducibility. Re-analysis of data from a human clinical trial that used maltodextrin as dietary placebo illustrated multimodal responses between human groups, and after placebo consumption. In conclusion, increasing N does not necessarily ensure reproducible statistical findings across repeated simulations due to randomness and multimodality. Herein, we clarify how to quantify, visualize and address disease data multimodality in research. Data visualization could facilitate study designs focused on disease subtypes/modes to help understand person–person differences and personalized medicine.

Evidence that a novel transdiagnostic eating disorder treatment reduces reward region response to the thin beauty ideal and high-calorie binge foods

2021 ◽  
pp. 1-11
Author(s):  
Eric Stice ◽  
Sonja Yokum ◽  
Paul Rohde ◽  
Jeff Gau ◽  
Heather Shaw
Keyword(s):  
Eating Disorder ◽  
Brain Imaging ◽  
Small Samples ◽  
Average Weight ◽  
Imaging Data ◽  
Eating Disorder Treatment ◽  
Disorder Treatment ◽  
Reward Valuation ◽  
Larger Sample ◽  
High Calorie

Abstract Background Findings from brain imaging studies with small samples can show limited reproducibility. Thus, we tested whether the evidence that a transdiagnostic eating disorder treatment reduces responsivity of brain valuation regions to thin models and high-calorie binge foods, the intervention targets, from a smaller earlier trial emerged when we recruited additional participants. Methods Women with DSM-5 eating disorders (N = 138) were randomized to the dissonance-based body project treatment (BPT) or a waitlist control condition and completed functional magnetic resonance imaging (fMRI) scans assessing neural response to thin models and high-calorie foods at pretest and posttest. Results BPT v. control participants showed significantly greater reductions in responsivity of regions implicated in reward valuation (caudate) and attentional motivation (precuneus) to thin v. average-weight models, echoing findings from the smaller sample. Data from this larger sample also provided novel evidence that BPT v. control participants showed greater reductions in responsivity of regions implicated in reward valuation (ventrolateral prefrontal cortex) and food craving (hippocampus) to high-calorie binge foods v. low-calorie foods, as well as significantly greater reductions in eating disorder symptoms, abstinence from binge eating and purging behaviors, palatability ratings for high calorie foods, monetary value for high-calorie binge foods, and significantly greater increases in attractiveness ratings of average weight models. Conclusions Results from this larger sample provide evidence that BPT reduces valuation of the thin ideal and high-calorie binge foods, the intervention targets, per objective brain imaging data, and produces clinically meaningful reductions in eating pathology.

scholarly journals Prosocial Identities and Youth Violence

2018 ◽  
Vol 56 (1) ◽  
pp. 84-128 ◽  
Author(s):  
Chongmin Na ◽  
Ray Paternoster
Keyword(s):  
Youth Violence ◽  
Negative Binomial ◽  
Violent Behavior ◽  
Empirical Work ◽  
Small Samples ◽  
Outcome Variable ◽  
Random Effects Models ◽  
Positive Effects ◽  
Nationally Representative ◽  
Mediation Processes

Objective: Despite a recent surge of interest in the important role that identity change plays in the desistance process, much of the empirical work has been qualitative and conducted with small samples, usually of serious adult offenders. Drawing on a nationally representative sample of adolescents in South Korea, this study explores how the development of their prosocial identity is related to their own social bond and network and collectively how this process relates to a downward trend in violent behavior. Method: Negative binomial random effects models were estimated to assess the within-individual effects of the proposed predictor and mediators on the outcome variable. Then, longitudinal path analyses were conducted to explore the overall and specific mediation processes. Conclusion: First, there is an inverse relationship between prosocial identity and violent behavior across time. Second, our own identity of self might not be entirely a social construction based on others’ appraisals but is intimately connected to the actions that we intentionally take. Third, positive effects of a prosocial identity on subsequent violence are mediated primarily by the avoidance of association with delinquent peers. Theoretical implications and limitations are discussed.

scholarly journals HOSPITAL ACQUIRED INFECTIONS

2010 ◽  
Vol 17 (02) ◽  
pp. 168-173
Author(s):  
SHAZIA QAYYUM ◽  
BUSHRA Waqas ◽  
ABDUL SATTAR
Keyword(s):  
Nosocomial Infections ◽  
Hospital Staff ◽  
Prevention Study ◽  
Basic Step ◽  
Hospital Acquired Infections ◽  
Different Types ◽  
Study Population ◽  
Study Designs ◽  
Hospital Acquired ◽  
Surgical Unit

Nosocomial infections may be defined as the infections which develop within hospital. There are different types of microorganisms which are involved along with other agents for the spread of these infections. Knowledge about the spread and prevention of these infections is the basic step for control. Hospital staff especially the doctors should be aware about the precautions to control the spread of there infections. Objectives: To assess the knowledge of doctors about hospital acquired infections and its prevention. Study designs: descriptive study Settings and period: In surgical unit of Allied Hospital Faisalabad from 15th June 2006 15th July 2006. Materials and methods: Study population was consisted on 71 doctors including Consultants, Medical Officers and House Officers. Data was collected with the help of questionnaires. Results: Results showed that majority of doctors were aware about nosocomial infections (N.I) but have weak knowledge about their routes of transmission and common types of N.I. Conclusions: The study revealed that doctors have sufficient knowledge regarding N.I and its prevention but certain weakness were observed.

scholarly journals HOSPITAL ACQUIRED INFECTIONS

2010 ◽  
Vol 17 (02) ◽  
pp. 168-173
Author(s):  
SHAZIA QAYYUM ◽  
BUSHRA WAQAS ◽  
ABDUL SATTAR
Keyword(s):  
Nosocomial Infections ◽  
Hospital Staff ◽  
Prevention Study ◽  
Basic Step ◽  
Hospital Acquired Infections ◽  
Different Types ◽  
Study Population ◽  
Study Designs ◽  
Hospital Acquired ◽  
Surgical Unit

Nosocomial infections may be defined as the infections which develop within hospital. There are different types of  microorganisms which are involved along with other agents for the spread of these infections. Knowledge about the spread and prevention of these infections is the basic step for control. Hospital staff especially the doctors should be aware about the precautions to control the spread of there infections. Objectives: To assess the knowledge of doctors about hospital acquired infections and its prevention. Study designs: descriptive study Settings and period: In surgical unit of Allied Hospital Faisalabad from 15th June 2006 15th July 2006. Materials and methods: Study population was consisted on 71 doctors including Consultants, Medical Officers and House Officers. Data was collected with the help of questionnaires. Results: Results showed that majority of doctors were aware about nosocomial infections (N.I) but have weakknowledge about their routes of transmission and common types of N.I. Conclusions: The study revealed that doctors have sufficient knowledge regarding N.I and its prevention but certain weakness were observed.

scholarly journals Examining the radius valley: a machine-learning approach

2019 ◽  
Vol 487 (4) ◽  
pp. 5062-5069 ◽  
Author(s):  
Mariah G MacDonald
Keyword(s):  
Kernel Density ◽  
Theoretical Models ◽  
Small Samples ◽  
Negative Slope ◽  
Density Estimator ◽  
Learning Approach ◽  
Clustering Methods ◽  
Machine Learning Approach ◽  
The Relationship ◽  
Larger Sample

ABSTRACT The ‘radius valley’ is a relative dearth of planets between two potential populations of exoplanets, super-Earths and mini-Neptunes. This feature appears in examining the distribution of planetary radii, but has only ever been characterized on small samples. The valley could be a result of photoevaporation, which has been predicted in numerous theoretical models, or a result of other processes. Here, we investigate the relationship between planetary radius and orbital period through two-dimensional kernel density estimator and various clustering methods, using all known super-Earths (R < 4.0RE). With our larger sample, we confirm the radius valley and characterize it as a power law. Using a variety of methods, we find a range of slopes that are consistent with each other and distinctly negative. We average over these results and find the slope to be $m=-0.319^{+0.088}_{-0.116}$. We repeat our analysis on samples from previous studies. For all methods we use, the resulting line has a negative slope, which is consistent with models of photoevaporation and core-powered mass-loss but inconsistent with planets forming in a gas-poor disc

Collaborative Study of the Comparison of Mineral Wool Insulations in the Forensic Laboratory

1977 ◽  
Vol 60 (4) ◽  
pp. 772-777
Author(s):  
Elmer T Miller
Keyword(s):  
Hydrochloric Acid ◽  
Collaborative Study ◽  
Mineral Wool ◽  
Small Samples ◽  
Matched Pairs ◽  
Microscopic Appearance ◽  
Large Samples ◽  
Heat Treated

Abstract A method for the comparison of mineral wool insulation specimens was studied collaboratively. Exemplar and questioned specimens are compared microscopically for color of resin, shapes and quantity of slugs or shot, relative fiber diameters, and other gross characteristics. Then the resin is burned off, and the fibers are annealed at 500°C. The heat-treated fibers are compared for shortwave ultraviolet fluorescence, microscopic appearance, solubility in dilute and concentrated hydrochloric acid, and refraction and dispcrsion indices according to 45.002–5.007. Eight collaborators in 6 laboratories compared 8 matched pairs of large samples (such as exemplars) and small samples (such as might be found on a suspect’s clothing).

Alignment of milliarcsecond with arcsecond scale structure in core-dominated radio sources

1986 ◽  
Vol 64 (4) ◽  
pp. 440-444 ◽  
Author(s):  
Raymond Rusk ◽  
Ann C.M. Rusk
Keyword(s):  
Scale Structure ◽  
Small Samples ◽  
Radio Sources ◽  
Angle Distribution ◽  
Long Baseline ◽  
Relativistic Beaming ◽  
Beam Parameters ◽  
Highly Correlated ◽  
Bend Angles ◽  
Larger Sample

Models of compact radio sources as relativistic jets aligned nearly along the line of sight predict large magnifications of intrinsic jet bends due to projection effects. Several authors have examined the distribution of observed bend angles, for small samples of sources, to provide constraints on the relativistic beaming models. In this study, we examine the alignment of Very Long Baseline Interferometry scale structure with arcsecond scale structure for a much larger sample of core-dominated radio sources and compare the distribution of observed misalignment angles with theoretical distributions calculated from models using a range of intrinsic bend angles, ξ, and Lorentz factors, γ. The theoretical distributions produced by simple relativistic beam models are found to be consistent with the data. However, the values of ξ and γ required to fit the data are highly correlated, with equally good fits produced by γ = 5, ξ = 11° and γ = 10, ξ = 5°, for instance. Either ξ or γ must be known independently for an analysis of the misalignment angle distribution to provide a significant constraint on beam parameters.

Applications of Microspectroscopy in the Near-Infrared Region

1989 ◽  
Vol 43 (5) ◽  
pp. 865-873 ◽  
Author(s):  
Matthew J. Smith ◽  
Richard T. Carl
Keyword(s):  
Near Infrared ◽  
Materials Science ◽  
Structural Information ◽  
Infrared Region ◽  
Small Samples ◽  
Infrared Analysis ◽  
Mid Infrared ◽  
Infrared Microspectroscopy ◽  
Different Types ◽  
Near Infrared Region

In this report, several applications of near-infrared microspectroscopy are illustrated using unmodified commercial instrumentation. The principal advantage of near-infrared microspectroscopy is the ability to analyze small samples which are totally absorbing in the mid-infrared region. Near-infrared analysis is shown to yield useful structural information about several different types of samples. Examples from the fields of materials science, single crystals, forensics and biological science are illustrated, and some tentative band assignments are made.

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