scholarly journals Volatility in International Stock Markets: An Empirical Study during COVID-19

2020 ◽  
Vol 13 (9) ◽  
pp. 208
Author(s):  
Rashmi Chaudhary ◽  
Priti Bakhshi ◽  
Hemendra Gupta
Keyword(s):  
Econometric Model ◽  
Central Tendency ◽  
International Stock Markets ◽  
Efficient Portfolios ◽  
The Mean ◽  
Garch Modeling ◽  
Autoregressive Conditional Heteroscedasticity ◽  
Bounce Back ◽  
Daily Returns ◽  
Mean Reverting Process

Predicting volatility is a must in the finance domain. Estimations of volatility, along with the central tendency, permit us to evaluate the chances of getting a particular result. Financial analysts are frequently challenged with the assignment of diversifying assets in order to form efficient portfolios with a higher risk to reward ratio. The objective of this research is to analyze the influence of COVID-19 on the return and volatility of the stock market indices of the top 10 countries based on GDP using a widely applied econometric model—generalized autoregressive conditional heteroscedasticity (GARCH). For this purpose, the daily returns of market indices from January 2019 to June 2020 were taken into consideration. The results reveal daily negative mean returns for all market indices during the COVID period (January 2020 to June 2020). Though the second quarter of the COVID period reflects a bounce back for all market indices with altered strengths, the volatility remains higher than in normal periods, signaling a bearish tendency in the market. The COVID variable, as an exogenous variance regressor in GARCH modeling, is found to be positive and significant for all market indices. Furthermore, the results confirmed the mean-reverting process for all market indices.

scholarly journals Congenital malformations in neonates: analysis of morbidity and associated factors

10.3823/2465 ◽  
2017 ◽  
Vol 10 ◽  
Author(s):  
Rosana Alves de Melo ◽  
Flávia Emília Cavalcante Valença Fernandes ◽  
Ana Kariny Costa Araújo ◽  
Nadja Maria dos Santos ◽  
Maria Elda Alves de Lacerda Campos ◽  
...  
Keyword(s):  
Congenital Malformations ◽  
Neonatal Morbidity ◽  
Normal Weight ◽  
Central Tendency ◽  
Chi Square ◽  
Level Of Education ◽  
The Mean ◽  
Upper Level ◽  
The City ◽  
Prenatal Visits

Objective: To evaluate the neonatal morbidity due to congenital malformations in the city of Petrolina-PE, from 2008 to 2013. Methods: A descriptive study with data from the Information System on Live Births (Sinasc). The analyzes were carried out through frequency distribution and measures of central tendency and dispersion. The associations were tested by the Pearson and Kruskal Wallis chi-square tests. Significance was set at 5% and 95% confidence. Results: 436 cases of congenital malformations were recorded in the study period, with 2011 being the highest occurrence year. The mothers of the newborns were young (25.2 years old), single, upper level of education and household. In general multiparous, with single gestation, vaginal delivery and performed up to six prenatal visits. The newborns were males, at 39 weeks or more of gestation and with normal weight (> = 2500g). The malformations of the musculoskeletal system were the most frequent followed by the genitourinary system. Congenital malformations were especially associated with neonatal characteristics such as gender and weight. In all causes the mean weight was greater than 2500g (p <0.05). The causes of malformation of greater occurrence in both sexes were osteomuscular (p <0.05). The aspects of the mother did not present significant differences in the present study (p> 0.05). Conclusion: The present study evidenced relevant aspects in the occurrence of morbidities due to congenital malformations, directing to a greater attention the occurrence of these diseases especially in relation to the newborn.

scholarly journals Land snails as experimental animals: a study of the variability and distribution of individual weights in Helix aspersa snails born from the same clutch

1990 ◽  
Vol 24 (1) ◽  
pp. 1-4 ◽  
Author(s):  
R. Sanz Sampelayo ◽  
J. Fonolla ◽  
F. Gil Extremera
Keyword(s):  
Normal Distribution ◽  
Growth Curve ◽  
Original Data ◽  
Helix Aspersa ◽  
Land Snails ◽  
Central Tendency ◽  
Experimental Conditions ◽  
Experimental Animals ◽  
Coefficients Of Variation ◽  
The Mean

A study was carried out to examine the distribution of individual weights in Helix aspersa snails, the aims being to establish the best estimate of the ponderal growth and also to obtain a model growth curve. Four groups of 20 snails from the same clutch were analysed and kept under experimental conditions from birth up to 6 months. The variability of their individual weights within groups was studied by calculating the coefficients of variation every 15 days. At the same time, the assumed normal distribution of those weights was being tested. The coefficients of variation increased with age and the assumed normal distribution of individual weights had to be rejected. By means of a log transformation of the original data, a model growth curve was constructed, and was used to assess the possibility of estimating age from weight. We finally reached the conclusion that median weight, rather than the mean, would be a better measure of central tendency to use until it is possible to obtain selected populations. The difficulty of estimating age from weight is emphasized.

15. Quantitative Analysis: Description and Inference

2020 ◽  
pp. 393-421
Author(s):  
Sandra Halperin ◽  
Oliver Heath
Keyword(s):  
Quantitative Analysis ◽  
Standard Deviation ◽  
Confidence Intervals ◽  
Quantitative Research ◽  
Building Blocks ◽  
Descriptive Statistics ◽  
Central Tendency ◽  
Margin Of Error ◽  
Univariate Statistics ◽  
The Mean

This chapter deals with quantitative analysis, and especially description and inference. It introduces the reader to the principles of quantitative research and offers a step-by-step guide on how to use and interpret a range of commonly used techniques. The first part of the chapter considers the building blocks of quantitative analysis, with particular emphasis on different ways of summarizing data, both graphically and with tables, and ways of describing the distribution of one variable using univariate statistics. Two important measures are discussed: the mean and the standard deviation. After elaborating on descriptive statistics, the chapter explores inferential statistics and explains how to make generalizations. It also presents the concept of confidence intervals, more commonly known as the margin of error, and measures of central tendency.

Portfolio selection and matching: a synthesis

1992 ◽  
Vol 119 (1) ◽  
pp. 87-105 ◽  
Author(s):  
M. Sherris
Keyword(s):  
Portfolio Selection ◽  
Life Insurance ◽  
General Framework ◽  
Pension Fund ◽  
Central Value ◽  
Efficient Portfolios ◽  
The Mean ◽  
Mean Variance ◽  
Special Case ◽  
Selection Of

AbstractThis paper considers a general framework for the selection of assets to meet the liabilities of a life insurance or pension fund. This general framework contains the mean-variance efficient portfolios of modern portfolio theory as a special case. The paper also demonstrates how the portfolio selection and matching approach of Wise (1984a, 1984b, 1987a, 1987b) and Wilkie (1985) fits into this general framework. The matching portfolio is derived as a special case, and is also shown to have implications for determining the central value of the liabilities.

scholarly journals Technical note: A nonparametric outlier rejection scheme

1992 ◽  
Vol 14 (1) ◽  
pp. 25-27 ◽  
Author(s):  
J. S. O. Odonde
Keyword(s):  
Measurement Errors ◽  
Low Frequency ◽  
Technical Note ◽  
Reliable Estimate ◽  
Central Tendency ◽  
Frequency Filtering ◽  
Outlier Rejection ◽  
Absolute Deviation ◽  
Data Set ◽  
The Mean

Experimental data always contains measurement errors (or noise, in signal processing). This paper is concerned with the removal of outliers from a data set consisting of only a handful of points. The data set has a unimodal probability distribution function, the mode is thus a reliable estimate of the central tendency. The approach is nonparametric; for the data set (xi, yi) only the ordinates (yi) are used. The abscissa (xi) are reparametrized to the variable i = 1, N.The data is bounded using a calculated mode and a new measure: the mean absolute deviation from the mode. This does not seem to have been reported before. The mean is removed and low frequency filtering is performed in the frequency domain, after which the mean is reintroduced.

scholarly journals Sample Size to Estimate the Mean and Median of Traits in Canola

2018 ◽  
Vol 10 (11) ◽  
pp. 123
Author(s):  
Alberto Cargnelutti Filho ◽  
Cleiton Antonio Wartha ◽  
Jéssica Andiara Kleinpaul ◽  
Ismael Mario Marcio Neu ◽  
Daniela Lixinski Silveira
Keyword(s):  
Sample Size ◽  
Aerial Part ◽  
Dry Matter ◽  
Central Tendency ◽  
Sample Sizes ◽  
Brassica Napus L ◽  
Fresh Matter ◽  
The Mean ◽  
Productive Traits ◽  
Larger Sample

The aim of this study was to determine the sample size (i.e., number of plants) required to estimate the mean and median of canola (Brassica napus L.) traits of the Hyola 61, Hyola 76, and Hyola 433 hybrids with precision levels. At 124 days after sowing, 225 plants of each hybrid were randomly collected. In each plant, morphological (plant height) and productive traits (number of siliques, fresh matter of siliques, fresh matter of aerial part without siliques, fresh matter of aerial part, dry matter of siliques, dry matter of aerial part without siliques, and dry matter of aerial part) were measured. For each trait, measures of central tendency, variability, skewness, and kurtosis were calculated. Sample size was determined by resampling with replacement of 10,000 resamples. The sample size required for the estimation of measures of central tendency (mean and median) varies between traits and hybrids. Productive traits required larger sample sizes in relation to the morphological traits. Larger sample sizes are required for the hybrids Hyola 433, Hyola 61, and Hyola 76, in this sequence. In order to estimate the mean of canola traits of the Hyola 61, Hyola 76 e Hyola 433 hybrids with the amplitude of the confidence interval of 95% equal to 30% of the estimated mean, 208 plants are required. Whereas 661 plants are necessary to estimate the median with the same precision.

scholarly journals Characteristics and Transmission Dynamics of COVID-19 in Resident Physicians at a Mexico City Teaching Hospital

2021 ◽  
Vol 2 (3) ◽  
pp. 72-76
Author(s):  
Jessica G. Azcorra-Lopez ◽  
Jesus Reyna-Figueroa ◽  
Eva M. Luna-Rivera ◽  
Berenice Cabañas-Espinosa ◽  
Yamile N. Esquivel-Torruco ◽  
...  
Keyword(s):  
Healthcare Workers ◽  
Infection Prevention ◽  
Case Control Study ◽  
Transmission Dynamics ◽  
Central Tendency ◽  
Resident Physicians ◽  
Significant Difference ◽  
The Mean ◽  
Control Study

Introduction: During the COVID-19 pandemic, hospitals have been busy controlling their spread among healthcare workers, including resident doctors. We seek to characterize and know the transmission dynamics of the SARS-COV-2 infection in the personnel of our hospital. Methodology: 204 resident physicians were followed up, in three parts: Part 1. Training, Part 2. follow-up through the WhatsApp application, Part 3. case-control study; looking for risk factors. The statistical analysis was carried out using measures of central tendency and dispersion, comparison of proportions and rates. As well as the calculation of the odds ratio with a 95% confidence interval; p <0.05 was considered significant. Results: 66 resident physicians were included, 31.8% had a positive result. The mean age was 28.9. The most frequent clinical manifestation was myalgia (66.6%), followed by headache (47%). When comparing with symptomatic resident physicians, with a negative test, there was a significant difference in arthralgia (p = 0.01) and dyspnea (0.05). Noncompliance with training (OR 7.0; 95% CI 2.2-26 and p = 0.000) was significant as a risk factor for infection. Conclusions: Resident physicians must be mostly supervised during infection prevention and containment training.

scholarly journals The impact of COVID-19 on the standard & poor 500 index sectors: a multivariate generalized autoregressive conditional heteroscedasticity model

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Maha Elhini ◽  
Rasha Hammam
Keyword(s):  
Significant Relation ◽  
Content Type ◽  
Daily Return ◽  
Technology Sector ◽  
Time Period ◽  
The Us ◽  
Us Dollar ◽  
The Impact ◽  
Autoregressive Conditional Heteroscedasticity ◽  
Daily Returns

Purpose This paper aims to examine the impact of the daily growth rate of COVID-19 cases in the USA (COVIDg), the Federal Fund Rate (FFR) and the trade-weighted US dollar index (USDX) on S&P500 index daily returns and its 11 constituent sectors’ indices for the time period between January 22, 2020, until June 30, 2020. Design/methodology/approach The study uses the multivariate generalized autoregressive conditional heteroscedasticity (MGARCH) model to gauge the impacts over the whole period of study, as well as over two sub-periods; first, January 22, 2020, until March 30, 2020, reflecting uncertainty in the US markets and second, from April 1, 2020, until June 30, 2020, reflecting the lockdown. Findings Results of the MGARCH model reveal a negative and significant relation between COVIDg and S&P500 index daily returns over the first sub-period and the whole study period in the following sectors, namely, communications, consumer discretionary, consumer staples, health, technology and materials. Yet, COVIDg showed a positive and significant relation with S&P500 index daily returns during the second time period in the following sectors, namely, communication, consumer discretionary, financial, industrial, information technology (IT) and utilities. Besides, USDX showed a negative significant effect on S&P500 index daily returns and on the daily return on each of its 11 constituent sectors over the second sub-period and the whole period. Further, FFR showed a significant effect only in the second sub-period, specifically, a negative effect on the daily return of the financial sector and a positive effect on the daily return of the technology sector index. Nevertheless, FFR had a positive significant effect on the daily return of the utilities sector index for the whole period under study. Research limitations/implications The impact of the crisis on the S&P500 index can be assessed only with some limitations owing to available global data and the limited time frame of the lock-down. Practical implications The study proposes supporting a smooth, functioning and resilient financial system; increasing fiscal measures by the US Government to increase liquidity on constraints; measures by The Federal Reserve to alleviate US dollar funding shortages; support market integrity; ensure continuous transparency and sharing of information; support the health sector, as well as consumer-based sectors that faced demand shocks and facilitate investments in the technology sector. Originality/value The originality of this paper lies in the examination of the impact of the novel COVID-19 pandemic on each of the 11 sectors constituting the S&P500 index separately, reflecting how the main economic sectors formulating the US economy reacted to the shock during the peak time of the pandemic to observe a full picture of the economic consequences amid the pandemic.

scholarly journals Profiling students’ environmental care attitudes taught using Sasak Tribe local wisdom-integrated model

2019 ◽  
Vol 5 (3) ◽  
Author(s):  
H. Hunaepi ◽  
Ika Nuraini Dewi ◽  
S. Sumarjan
Keyword(s):  
Sampling Technique ◽  
Integrated Model ◽  
Descriptive Statistics ◽  
Central Tendency ◽  
Mean Values ◽  
Environmental Care ◽  
Descriptive Research ◽  
Analysis Technique ◽  
The Mean

Sasak Tribe possesses unique local wisdom which is potential to be utilized in term of improving students' care attitudes toward the environment. This study aimed at profiling students' evironmental attitudes who were taught using Sasak Tribe local wisdom-integrated model. This descriptive research was designed with a one-shot case study. The sample used in this study was 140 VII graders chosen using random sampling technique. The sample comprised of 3 classes of SMPN 2 Gunung Sari and 3 classes of SMPN 3 Lingsar placed in West Nusa Tenggara-Indonesia. The data analysis technique used was descriptive statistics in term of central tendency. The measured indicators were environmental awareness (EA), developing empathy (DE), and effect handling (EH). The results showed that the students live in suburb area tended to have better environmental care attitudes, in which the mean values were 86.66 (EA), 75.69 (DE), and 42.66 (EH) compared to those who live in urban area in which the mean values were 68.73 (EA), 57.07 (DE), and 30.62 (EH). Based on this findings, further evaluation in several aspects should be done.

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