scholarly journals Field Significance Revisited: Spatial Bias Errors in Forecasts as Applied to the Eta Model

2006 ◽  
Vol 134 (2) ◽  
pp. 519-531 ◽  
Author(s):  
Kimberly L. Elmore ◽  
Michael E. Baldwin ◽  
David M. Schultz
Keyword(s):  
Statistical Significance ◽  
Bootstrap Method ◽  
Bias Error ◽  
Forecast Errors ◽  
Spatial Bias ◽  
Significance Level ◽  
Spatially Correlated ◽  
The Face ◽  
Moving Blocks Bootstrap ◽  
Eta Model

Abstract The spatial structure of bias errors in numerical model output is valuable to both model developers and operational forecasters, especially if the field containing the structure itself has statistical significance in the face of naturally occurring spatial correlation. A semiparametric Monte Carlo method, along with a moving blocks bootstrap method is used to determine the field significance of spatial bias errors within spatially correlated error fields. This process can be completely automated, making it an attractive addition to the verification tools already in use. The process demonstrated here results in statistically significant spatial bias error fields at any arbitrary significance level. To demonstrate the technique, 0000 and 1200 UTC runs of the operational Eta Model and the operational Eta Model using the Kain–Fritsch convective parameterization scheme are examined. The resulting fields for forecast errors for geopotential heights and winds at 850, 700, 500, and 250 hPa over a period of 14 months (26 January 2001–31 March 2002) are examined and compared using the verifying initial analysis. Specific examples are shown, and some plausible causes for the resulting significant bias errors are proposed.

The Impact of The Covid-19 Pandemic on Investor Risk Tendency: The Case of Turkey

2021 ◽  
Vol 15 (9) ◽  
pp. 3046-3049
Author(s):  
Abdulkadir Kaya
Keyword(s):  
Risk Perceptions ◽  
Time Series Data ◽  
Statistical Significance ◽  
Series Data ◽  
Causality Test ◽  
Significance Level ◽  
Risk Appetite ◽  
Central Registry ◽  
The Face ◽  
The Impact

Introduction and Aim: It is an important issue that what kind of changes occur in the risks that people face in the face of emerging problems and the role of people in possible pandemics in the last twenty years and in the future. The solution of the problems that arise in the control and management of these risks attracts the attention of many researchers. In this study, the causality effect of the COVID-19 pandemic on risk appetites representing the attitudes and behaviors of securities investors. Materials and Methods: In the study; To represent the pandemic, weekly time series data of the number of COVID-19 cases (COVID) and the Risk Appetite index (RISK) announced by the Central Registry Agency for the period 30.03.2019-30.08.2021 were used. In order to determine the causality relationship, the Hatemi-J Causality test was performed. Results: It was determined that the negative shocks of the COVID variable were a cause of the positive shocks of the RISK variable at a statistical significance level of 1%. Conclusion and Suggestions: The effect of the pandemic process on the investment decisions of the investors is reduced, with the expectation that the economy and financial markets will improve, positively affecting the behavior and risk perceptions of the investors, and this expectation causes the investment behavior and risk appetite to increase. can be expressed. Keywords: COVID-19, Risk appetite, Pandemic, Hatemi-J

scholarly journals Using the Bootstrap Method for a Statistical Significance Test of Differences between Summary Histograms

2006 ◽  
Vol 134 (5) ◽  
pp. 1442-1453 ◽  
Author(s):  
Kuan-Man Xu
Keyword(s):  
Euclidean Distance ◽  
Probability Distributions ◽  
Statistical Tests ◽  
Statistical Significance ◽  
Bootstrap Method ◽  
Statistical Hypothesis ◽  
Object Size ◽  
Size Category ◽  
Significance Level ◽  
The Bootstrap Method

Abstract A new method is proposed to compare statistical differences between summary histograms, which are the histograms summed over a large ensemble of individual histograms. It consists of choosing a distance statistic for measuring the difference between summary histograms and using a bootstrap procedure to calculate the statistical significance level. Bootstrapping is an approach to statistical inference that makes few assumptions about the underlying probability distribution that describes the data. Three distance statistics are compared in this study. They are the Euclidean distance, the Jeffries–Matusita distance, and the Kuiper distance. The data used in testing the bootstrap method are satellite measurements of cloud systems called “cloud objects.” Each cloud object is defined as a contiguous region/patch composed of individual footprints or fields of view. A histogram of measured values over footprints is generated for each parameter of each cloud object, and then summary histograms are accumulated over all individual histograms in a given cloud-object size category. The results of statistical hypothesis tests using all three distances as test statistics are generally similar, indicating the validity of the proposed method. The Euclidean distance is determined to be most suitable after comparing the statistical tests of several parameters with distinct probability distributions among three cloud-object size categories. Impacts on the statistical significance levels resulting from differences in the total lengths of satellite footprint data between two size categories are also discussed.

scholarly journals Can innovative trend analysis identify trend change points?

2020 ◽  
Vol 1 (3) ◽  
pp. 6-15
Author(s):  
Sadık Alashan
Keyword(s):  
Time Series ◽  
Trend Analysis ◽  
Statistical Significance ◽  
Bootstrap Method ◽  
Change Points ◽  
Trend Detection ◽  
Significance Level ◽  
Related Data ◽  
Innovative Trend Analysis ◽  
June July

Trends in temperature series are the main cause of climate change. Because solar energy directs hydro-meteorological events and increasing variations in this resource change the balance between events such as evaporation, wind, and rainfall. There are many methods for calculating trends in a time series such as Mann-Kendall, Sen's slope estimator, Spearman's rho, linear regression and the new Sen innovative trend analysis (ITA). In addition, Mann-Kendall's variant, the sequential Mann Kendall, has been developed to identify trend change points; however, it is sensitive to related data as specified by some researchers. Şen_ITA is a new trend detection method and does not require independent and normally distributed time series, but has never been used to detect trend change points. In the literature, multiple, half-time and multi-durations ITA methods are used to calculate partial trends in a time series without identifying trend change points. In this study, trend change points are detected using the Şen_ITA method and named ITA_TCP. This approach may allow researchers to identify trend change points in a time series. Diyarbakır (Turkey) is selected as a study area, and ITA_TCP has detected trends and trends change points in monthly average temperatures. Although ITA detects only a significant upward trend in August, given the 95% statistical significance level, ITA_TCP shows three upward trends in June, July and August, and a decreasing trend in September. Critical trend slope values are obtained using the bootstrap method, which does not require the normal distribution assumption.

scholarly journals Can innovative trend analysis identify trend change points?

2020 ◽  
Vol 1 (3) ◽  
pp. 6-15
Author(s):  
Sadık Alashan
Keyword(s):  
Time Series ◽  
Trend Analysis ◽  
Statistical Significance ◽  
Bootstrap Method ◽  
Change Points ◽  
Trend Detection ◽  
Significance Level ◽  
Related Data ◽  
Innovative Trend Analysis ◽  
June July

Trends in temperature series are the main cause of climate change. Because solar energy directs hydro-meteorological events and increasing variations in this resource change the balance between events such as evaporation, wind, and rainfall. There are many methods for calculating trends in a time series such as Mann-Kendall, Sen's slope estimator, Spearman's rho, linear regression and the new Sen innovative trend analysis (ITA). In addition, Mann-Kendall's variant, the sequential Mann Kendall, has been developed to identify trend change points; however, it is sensitive to related data as specified by some researchers. Şen_ITA is a new trend detection method and does not require independent and normally distributed time series, but has never been used to detect trend change points. In the literature, multiple, half-time and multi-durations ITA methods are used to calculate partial trends in a time series without identifying trend change points. In this study, trend change points are detected using the Şen_ITA method and named ITA_TCP. This approach may allow researchers to identify trend change points in a time series. Diyarbakır (Turkey) is selected as a study area, and ITA_TCP has detected trends and trends change points in monthly average temperatures. Although ITA detects only a significant upward trend in August, given the 95% statistical significance level, ITA_TCP shows three upward trends in June, July and August, and a decreasing trend in September. Critical trend slope values are obtained using the bootstrap method, which does not require the normal distribution assumption.

The Impact of The Covid-19 Pandemic on Investor Risk Tendency: The Case of Turkey

2021 ◽  
Vol 15 (10) ◽  
pp. 2941-2944
Author(s):  
Abdulkadir kaya
Keyword(s):  
Risk Perceptions ◽  
Time Series Data ◽  
Statistical Significance ◽  
Series Data ◽  
Causality Test ◽  
Significance Level ◽  
Risk Appetite ◽  
Central Registry ◽  
The Face ◽  
The Impact

Introduction and Aim: It is an important issue that what kind of changes occur in the risks that people face in the face of emerging problems and the role of people in possible pandemics in the last twenty years and in the future. The solution of the problems that arise in the control and management of these risks attracts the attention of many researchers. In this study, the causality effect of the COVID-19 pandemic on risk appetites representing the attitudes and behaviors of securities investors. Materials and Methods: In the study; To represent the pandemic, weekly time series data of the number of COVID-19 cases (COVID) and the Risk Appetite index (RISK) announced by the Central Registry Agency for the period 30.03.2019-30.08.2021 were used. In order to determine the causality relationship, the Hatemi-J Causality test was performed. Results: It was determined that the negative shocks of the COVID variable were a cause of the positive shocks of the RISK variable at a statistical significance level of 1%. Conclusion and Suggestions: The effect of the pandemic process on the investment decisions of the investors is reduced, with the expectation that the economy and financial markets will improve, positively affecting the behavior and risk perceptions of the investors, and this expectation causes the investment behavior and risk appetite to increase. can be expressed. Keywords: COVID-19, Risk appetite, Pandemic, Hatemi-J

Skull and Face Injuries and Associated Factors in Pedestrian Victims of Traffic Accidents: A Single Trauma Center Analysis

2020 ◽  
Vol 2 (1) ◽  
pp. 53-59
Author(s):  
Josimara A. de Araújo Varela ◽  
Tatiana F.T. Palitot ◽  
Smyrna L.X. de Souza ◽  
Alidianne F.C. Cavalcanti ◽  
Alessandro L. Cavalcanti
Keyword(s):  
Medical Records ◽  
Associated Factors ◽  
Traffic Accidents ◽  
Age Group ◽  
Chi Square ◽  
Cross Sectional ◽  
Significance Level ◽  
The Face ◽  
Chi Square Test ◽  
The City

Objective: This study aimed to analyze the presence of lesions in the skull and face and the associated factors in pedestrian victims of traffic accidents. Methods: A cross-sectional, descriptive-analytical study carried out through the analysis of medical records of pedestrian victims of traffic accidents in an emergency service in the city of Campina Grande, Brazil, during the year of 2016. Information was collected regarding gender, age group, day of the week, time of the accident, type of vehicle involved, presence of trauma to the skull and face, and outcomes. The Chi-square and Fisher's Exact tests were used, with a significance level of 5%. Results: A total of 1,884 medical records were evaluated, out of which 7.1% (n = 133) involved pedestrians. Men were the most frequent victims (68.4%), and victims of age 60 years old or over (30.5%) predominated. Almost one-third of the cases were recorded during the weekends (30.5%), and the most prevalent time was at night (52.7%). Regarding the type of vehicle involved, motorcycles predominated (47.4%). Head trauma was present in 37.6% of victims, while facial injuries corresponded to 8.2%. In 12% of cases, the victims died. The variables of gender, age group, occurrence on weekends, and trauma to the face showed a statistically significant association with the occurrence of traffic accidents (Chi-square test; p<0.05). Conclusion: Among pedestrian victims of traffic accidents, there is a predominance of men aged 65 years or over. Accidents are frequent at night, and motorcycles are the main vehicles involved. The presence of trauma to the skull and face regions is high.

scholarly journals Does daily wear time of Twin Block reliably predict its efficiency of class II treatment?

2021 ◽  
Author(s):  
Michal Sarul ◽  
Marek Nahajowski ◽  
Grzegorz Gawin ◽  
Joanna Antoszewska-Smith
Keyword(s):  
Statistical Significance ◽  
Characteristic Curve ◽  
Class Ii ◽  
Class I ◽  
Rank Test ◽  
Treatment Efficiency ◽  
Significance Level ◽  
Twin Block ◽  
Wear Time ◽  
Class Ii Treatment

Abstract Purpose The objective of this study was to investigate how daily wear time (DWT) influences class II malocclusion treatment efficiency. Materials and methods The study group consisted of 55 patients (mean age 10.4 years) diagnosed with a class II/1 malocclusion. Twin block appliances, with built-in Theramon® microsensors (MC Technology, Hargelsberg, Austria) to monitor patients’ cooperation (daily wear time assessment), were used for treatment. Cephalograms were taken and the following initial and final measurements were compared: Co-Gn, Co-Go, Co-Olp, Pg-Olp, WITS, SNA, SNB, ANB, Co-Go-Me, overjet, molar and canine relationships. The Shapiro–Wilk test, Wilcoxon signed-rank test, Student’s t-test, Levene’s test, Mann–Whitney U test, Kruskal–Wallis test, χ2 test, and Spearman’s rank correlation coefficient with p < 0.05 set as the statistical significance level were used to determine the correlation of the outcomes with DWT; a ROC (receiver operating characteristic) curve was calculated to illustrate diagnostic ability of the binary classifier system. Results DWT was very highly positively correlated with change of the Pg-Olp parameter and highly with an improvement in the ANB, SNA, and SNB angles, an increase in the WITS parameter and an increase in Co-Gn distance. DWTs < 7.5 h correlated with significantly less improvement of the investigated variables. However, DWT > 7.5 h did not significantly correlate with the improvement of the overjet and most of the linear parameters in the mandible. The ROC curve and its AUC (area under curve) allowed the determination of a DWT of 7 h and 48 min to be capable of establishing a class I relationship with 83% probability. Conclusions Class II treatment efficiency was influenced by DWT; an 8 h threshold value had an 83% probability of establishing a class I relationship.

scholarly journals Association of placental chorangiosis with pregnancy complication and prenatal outcome: a case-control study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Homeira Vafaei ◽  
Zinat Karimi ◽  
Mojgan Akbarzadeh-Jahromi ◽  
Fatemeh Asadian
Keyword(s):  
Case Control Study ◽  
Gestational Hypertension ◽  
Statistical Significance ◽  
Placental Tissue ◽  
Case Control ◽  
Low Grade ◽  
Amniotic Fluid Index ◽  
Significance Level ◽  
Adverse Pregnancy ◽  
Control Study

Abstract Background Chorangiosis is a vascular change involving the terminal chorionic villi in the placenta. It results from longstanding, low-grade hypoxia in the placental tissue, and is associated with such conditions as intrauterine growth restriction (IUGR), diabetes, and gestational hypertension in pregnancy. Chorangiosis rarely occurs in normal pregnancies. However, its prevalence is 5–7% of all placentas from infants admitted to newborn intensive care units. The present study was aimed at determining the association of chorangiosis with pregnancy complications and perinatal outcomes. Methods In this case-control study, 308 chorangiosis cases were compared with 308 controls (with other diagnoses in pathology) in terms of maternal, placental, prenatal, and neonatal characteristics derived from the medical records of participants retrospectively. R and SPSS version 22 software tools were used, and the statistical significance level was considered 0.05 for all the tests. Results Preeclampsia, diabetes mellitus, maternal hemoglobin, maternal hematocrit, C/S, oligohydramnios, fetal anomaly, dead neonates, NICU admissions were significantly higher in the chorangiosis group OR = 1.6, 3.98, 1.68, 1.92, 2.1, 4.47, 4.22, 2.9, 2.46, respectively (p-value< 0.05 for all). Amniotic fluid index, birth weight, cord PH amount, 1st, and 5th Apgar score was lower in the chorangiosis group OR = 0.31, 1, 0.097, 0.83, 0.85, respectively (p-value< 0.05 for all). Moreover, fundal placenta, retro placental hemorrhage, perivillous fibrin deposition, calcification, and acute chorioamnionitis were higher in the chorangiosis group OR = 2.1, 11.8, 19.96, 4.05, and 6.38 respectively, (p-value< 0.05). There was a high agreement between the two pathologists, and the power of the study was estimated at 99%. Conclusion Although chorangiosis is an uncommon condition, it is associated with a higher incidence of perinatal and neonatal morbidity and mortality. Therefore, it should be considered an important clinical sign of adverse pregnancy outcomes and should be reported in the pathology evaluation.

scholarly journals THU0652-HPR ONLINE EDUCATION YIELDS SIGNIFICANT GAINS IN RHEUMATOLOGISTS’ KNOWLEDGE OF BIOLOGICS AND BIOSIMILARS BUT A SUBSTANTIAL GAP REMAINS

2020 ◽  
Vol 79 (Suppl 1) ◽  
pp. 570.2-571
Author(s):  
A. Stan ◽  
E. Bell ◽  
P. Schoonheim ◽  
E. Mysler
Keyword(s):  
Online Education ◽  
Statistical Significance ◽  
Treatment Options ◽  
Educational Activity ◽  
Round Table Discussion ◽  
Knowledge Gain ◽  
Regulatory Requirements ◽  
Research Support ◽  
Significance Level ◽  
Post Assessment

Background:Biologics are complex proteins which have revolutionized the treatment of many serious diseases. Due to their complexity and manufacturing which involves living organisms, it is not possible to create identical versions of reference biologics, but it is possible to create biosimilar drugs. Biosimilars have the potential to yield high cost savings and expand treatment options to meet the growing demand for biological therapies.Objectives:This study assessed whether the online CME-accredited round-table-discussion titled “Understanding Biologics: from protein to clinical practice” improved physicians’ understanding of the inherent variability of biologics and what similarity means in the context of biologics as well as the analytical assessment of quality that applies to both biologics and biosimilars.Methods:Rheumatologists participated in an online CME activity (www.medscape.org/viewarticle/900121) consisting of a 30-minute video discussion between 4 experts with accompanying slides. Educational effect was assessed using a 4-question repeated pairs, pre-/post-assessment. A chi-square test was used to determine if a statistically significant improvement (P<.05 significance level) existed in the number of pre-/post-test correct responses. Cramer’s V was used to estimate the level of impact of the education. The CME activity launched on 22 Aug 2018, and the data were collected through 9 Oct 2018.Results:A total of 622 rheumatologists participated in the educational activity, and 87 completed the pre- and postassessment. Overall the activity had a signficiant impact (P<.001) on rheumatologists’ understanding of the inherent variability of biologics and the regulatory requirements for approval of a biosimilar. The Cramer’s V value of 0.186 indicates a considerable effect of the education. The average perecentage of correct responses rose from 33% pre-activity to 51% post-activity. A linked learning assessment (individual responses matched pre- and post-education) showed that 25% of learners improved their knowledge and 26% reinforced their knowledge. The change in percentage of correct responses from pre- to post-assessment achieved statistical significance (P<.05) in 2 of the 3 questions presented: (i) understanding the type of studies needed to demonstrate comparability of a biosimilar to an originator (11% at baseline; 45% post activity), (ii) understanding the type of variability considered acceptable for a biologic (46% at baseline; 63% post activity). However, no knowledge gain was observed regarding basic analytic attributes evaluated to ensure batch to batch consistency (37% at baseline; 38% post activity). Almost 45% of rheumatologists gained confidence in their ability to describe the regulatory requirements for approval of a biosimilar.Conclusion:This online CME activity significantly improved rheumatologists’ understanding of the inherent variability of complex biologic medicines and the role of analytical studies in the regulatory approval of biosimilars. However, there is room for further improving physicians’ knowledge, especially of basic analytics of biologics and biosimilars.Acknowledgments:This CME-certified activity was supported by independent funding from Sandoz.Disclosure of Interests:Adriana Stan Grant/research support from: The CME-certified activity was supported by anindependent educational grant from Sandoz., Elaine Bell: None declared, Peter Schoonheim Grant/research support from: This CME-certified activity was supported by independent funding from Sandoz., Eduardo Mysler Grant/research support from: AbbVie, Lilly, Pfizer, Roche, BMS, Sandoz, Amgen, and Janssen., Consultant of: AbbVie, Lilly, Pfizer, Roche, BMS, Sandoz, Amgen, and Janssen.

scholarly journals Association of ADRB1 gene polymorphism with dilated cardiomyopathy

2021 ◽  
Vol 10 (Supplement_1) ◽  
Author(s):  
A Chernova ◽  
SY Nikulina ◽  
OO Kuznecova
Keyword(s):  
Statistical Significance ◽  
Rare Allele ◽  
Public Institution ◽  
Control Group ◽  
Significance Level ◽  
Funding Sources ◽  
Idiopathic Cardiomyopathy ◽  
Homozygous Genotype ◽  
Number Of Patients ◽  
Medical University

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Prof. V.F. Voino-Yasenetsky Krasnoyarsk State Medical University Aim. To evaluate the Association of rs1801252 polymorphism of the ADRB1 gene with dilated idiopathic cardiomyopathy (DCMP) and myocardial dilation of ischemic origin (DMI). Subjects and methods. The study included patients with ICMP and MD IG in the number of 221 people. The average age of the subjects was in the range of 55.30 ± 9.69 years. We divided the patients into 2 groups: the first – patients diagnosed with idiopathic dilatation cardiomyopathy and the second-patients with myocardial dilatation of ichemic origin. The number of patients in the first group was 111, including 99 men (89.2%) and 12 women (10.8%). The average age of patients in this group is 51.73 ± 9.74 years, in men 51.00 ± 8.96 years, in women 57.75 ± 3.71 years. The second group included patients with myocardial dilatation of ischemic origin. Their number is 110 people, including 100 men (91.5%) and 10 women (8.5%). The average age of respondents is 58.68 ± 8.38 years, for men 58.29 ± 8.46 years, for women 62.90 ± 6.29 years. The control group included patients who had no manifestations of cardiovascular diseases. Their number is 121 people (average age 53.6 ± 4.8 years). The patients underwent laboratory and instrumental studies, as well as molecular and genetic studies of the A145G polymorphism of the ADRB1 gene (rs1801252 ). All patients underwent coronary angiography. Based on the anamnesis data and instrumental studies, those patients who could be said to have no risk factors for the development of dilatation of the heart cavities were identified in the first group. And those patients who were reliably diagnosed with CHD were in the second group, that is, dilatation of the heart cavities is due to a previous myocardial infarction, existing angina pectoris. Results. In the group with DCMP 70.3% of patients were carriers of the common homozygous A145A genotype, the heterozygous A145G genotype-27.0%, and the rare homozygous G145G genotype-2.7%. In the control group 71.9% of patients were identified as carriers of a homozygous genotype by a common allele, and 25.3% were carriers heterozygous genotype, and homozygous genotype for a rare allele – 2.7%. Statistical analysis showed no achievement of statistical significance level across any of the genotypes. In the group with DM IG, there was no association with the rs1801252 polymorphism of the ADRB1 gene. Conclusion. A statistically significant association of rs1801252 of the ADRB1 gene with DCMP was not found. The association of DM IG c rs1801252 could not be confirmed.

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