scholarly journals Relações Entre Correlação Serial e Volatilidade: Existe o Efeito LeBaron no Brasil?

2014 ◽  
Vol 12 (1) ◽  
pp. 13
Author(s):  
Regis Augusto Ely
Keyword(s):  
Empirical Evidence ◽  
Behavioral Finance ◽  
Serial Correlation ◽  
Empirical Studies ◽  
Variance Ratio ◽  
Positive Relation ◽  
Stylized Facts ◽  
Negative Relation ◽  
First Order ◽  
Daily Returns

This paper examines the relation between serial correlation and volatility of the Ibovespa index returns and extends the empirical evidence of the LeBaron effect for higher orders of serial correlation. We employ an exponential general autoregressive conditional heteroskedastic model to estimate volatility and an automatic variance ratio statistic to calculate serial correlation. The results support some stylized facts from behavioral finance and help us to explain evidences from empirical studies. We show that (i) serial correlation in weekly returns are negative related with volatility, (ii) this negative relation is found in daily returns only if we use first order serial correlation, and (iii) the effect for weekly returns was not intensified by the 2008 crisis, but a positive relation between volatility and serial correlation for daily returns was identified during that time.

Dynamic Moral Hazard and Risk-Shifting Incentives in a Leveraged Firm

2019 ◽  
Vol 55 (4) ◽  
pp. 1333-1367 ◽  
Author(s):  
Alejandro Rivera
Keyword(s):  
Moral Hazard ◽  
Empirical Studies ◽  
Risk Shifting ◽  
Optimal Contract ◽  
Positive Relation ◽  
Negative Relation ◽  
Moral Hazard Problem ◽  
Hazard And Risk ◽  
Incentive Constraint ◽  
Monotonic Relation

I develop an analytically tractable model that integrates the risk-shifting problem between bondholders and shareholders with the moral-hazard problem between shareholders and the manager. An optimal contract binds shareholders and the manager, and this contract’s flexibility allows shareholders to relax the manager’s incentive constraint following a “good” profitability shock. Thus, the optimal contract amplifies the upside and thereby increases shareholder appetite for risk shifting. Whereas some empirical studies find a positive relation between risk shifting and leverage, others find a negative relation. This model predicts a non-monotonic relation between risk shifting and leverage and can reconcile these contradictory empirical findings.

Spotting a liar by looking for microexpressions: Challenges and Opportunities

2019 ◽  
Author(s):  
Xunbing Shen
Keyword(s):  
Empirical Evidence ◽  
Deception Detection ◽  
Empirical Studies ◽  
High Stake ◽  
Challenges And Opportunities ◽  
Cues To Deception ◽  
The Relationship

Microexpressions do exist, and they are regarded as valid cues to deception by many researchers, furthermore, there is a lot of empirical evidence which substantiates this claim. However, some researchers don’t think the microexpression can be a way to catch a liar. The author elucidates the theories predicting that looking for microexpressions can be a way to catch a liar, and notes that some data can support for the utilization of microexpressions as a good way to detect deception. In addition, the author thinks that the mixed results in the area of investigating microexpressions and deception detection may be moderated by the stake. More empirical studies which employ high-stake lies to explore the relationship between microexpressions and deception detection are needed.

Assessing Medical Evidence

2018 ◽  
Author(s):  
Jacob Stegenga
Keyword(s):  
Quality Assessment ◽  
Randomized Trials ◽  
Empirical Studies ◽  
Allocation Concealment ◽  
Assessment Tools ◽  
Medical Evidence ◽  
Empirical Methods ◽  
First Order ◽  
First Order Methods

Medical scientists employ ‘quality assessment tools’ to assess evidence from medical research, especially from randomized trials. These tools are designed to take into account methodological details of studies, including randomization, subject allocation concealment, and other features of studies deemed relevant to minimizing bias. There are dozens of such tools available. They differ widely from each other, and empirical studies show that they have low inter-rater reliability and low inter-tool reliability. This is an instance of a more general problem called here the underdetermination of evidential significance. Disagreements about the quality of evidence can be due to different—but in principle equally good—weightings of the methodological features that constitute quality assessment tools. Thus, the malleability of empirical research in medicine is deep: in addition to the malleability of first-order empirical methods, such as randomized trials, there is malleability in the tools used to evaluate first-order methods.

Acquiring “Knowledge”—An Alternative Model

2017 ◽  
Author(s):  
Avner Baz
Keyword(s):  
Language Acquisition ◽  
Empirical Evidence ◽  
Alternative Model ◽  
Empirical Studies ◽  
First Language ◽  
Analytic Philosophy ◽  
Empirical Science ◽  
First Language Acquisition ◽  
Method Of Cases ◽  
Striking Fact

The chapter argues that empirical studies of first-language acquisition lend support to the Wittgensteinian-Merleau-Pontian conception of language as against the prevailing conception that underwrites the method of cases in either its armchair or experimental version. It offers a non-representationalist model, inspired by the work of Michael Tomasello, for the acquisition of “knowledge,” with the aim of showing that we could fully account for the acquisition of this and other philosophically troublesome words without positing independently existing “items” to which these words refer. The chapter also aims at bringing out and underscoring the striking fact that, whereas many in contemporary analytic philosophy regard and present themselves as open and attentive to empirical science, they have often relied on a conception of language that has been supported by no empirical evidence.

Factors affecting behavioural disturbances in race-horses

1998 ◽  
Vol 66 (2) ◽  
pp. 475-481 ◽  
Author(s):  
I. Redbo ◽  
P. Redbo-Torstensson ◽  
F. O. Ödberg ◽  
A. Hedendahl ◽  
J. Holm
Keyword(s):  
External Factors ◽  
Small Field ◽  
Positive Relation ◽  
Main Study ◽  
Social Contacts ◽  
Factors Affecting ◽  
Negative Relation ◽  
Stereotyped Behaviours ◽  
Race Horses ◽  
And Training

AbstractThe aim of the present study was to identify relations between stereotyped behaviours (cribbing, weaving and box-walking) and wood-chewing in thoroughbred flat-racing horses (TB) and standardbred trotters and the different management, feeding and training factors to which these horses are exposed. This was obtained by inquiries to all the professional trainers of TB and trottinghorses used for racing in Sweden. The usable response rates were 61% for trotters and 72% for TB representing 4597 trotters from 234 stables and 644 TB from 38 stables. A small field study was carried out to control the validity of the main study which gave results similar to those in the main study. There was a large difference between the two horse categories in the occurrence of behavioural disturbances. The TB had significantly more stereotypies than the trotters (P < 0·001) but there were no differences in the occurrence of wood-chewing. There were several differences in external factors between the horse categories, e.g. trotters had more opportunities for social contacts with other horses, they also had more free time outside the stable and they were trained a shorter time per week than the TB. The TB were given larger amounts of concentrate than the trotters. Wood-chewing within each horse category was explained by the amount of roughage (P < 0·05 in trotters and P < 0·001 in TB) together with other factors. Stereotypies in the TB were explained by: amount of concentrate (positive relation), number of horses per trainer (positive relation) and amount of roughage (negative relation).

The Relationship Between Proof and Certainty in Mathematical Practice

2022 ◽  
Vol 53 (1) ◽  
pp. 65-84
Keyword(s):  
Empirical Evidence ◽  
Doctoral Students ◽  
Empirical Studies ◽  
Mathematical Practice ◽  
Advanced Mathematics ◽  
Mathematics Educators ◽  
The Relationship

Many mathematics educators believe a goal of instruction is for students to obtain conviction and certainty in mathematical statements using the same types of evidence that mathematicians do. However, few empirical studies have examined how mathematicians use proofs to obtain conviction and certainty. We report on a study in which 16 advanced mathematics doctoral students were given a task-based interview in which they were presented with various sources of evidence in support of a specific mathematical claim and were asked how convinced they were that the claim was true after reviewing this evidence. In particular, we explore why our participants retained doubts about our claim after reading its proof and how they used empirical evidence to reduce those doubts.

scholarly journals Diversity–disturbance relationships: frequency and intensity interact

2012 ◽  
Vol 8 (5) ◽  
pp. 768-771 ◽  
Author(s):  
Alex R. Hall ◽  
Adam D. Miller ◽  
Helen C. Leggett ◽  
Stephen H. Roxburgh ◽  
Angus Buckling ◽  
...  
Keyword(s):  
Species Diversity ◽  
Empirical Evidence ◽  
Empirical Studies ◽  
Ecological Theory ◽  
Intermediate Disturbance Hypothesis ◽  
Intermediate Disturbance ◽  
Disturbance Frequency ◽  
Theoretical Predictions ◽  
Experimental Populations ◽  
Disturbance Hypothesis

An influential ecological theory, the intermediate disturbance hypothesis (IDH), predicts that intermediate levels of disturbance will maximize species diversity. Empirical studies, however, have described a wide variety of diversity–disturbance relationships (DDRs). Using experimental populations of microbes, we show that the form of the DDR depends on an interaction between disturbance frequency and intensity. We find that diversity shows a monotonically increasing, unimodal or flat relationship with disturbance, depending on the values of the disturbance aspects considered. These results confirm recent theoretical predictions, and potentially reconcile the conflicting body of empirical evidence on DDRs.

The Aftermath of Suicide: A Review of Empirical Evidence

1990 ◽  
Vol 20 (2) ◽  
pp. 149-171 ◽  
Author(s):  
Jan van der Wal
Keyword(s):  
Empirical Evidence ◽  
Causes Of Death ◽  
Empirical Studies ◽  
Prolonged Grief ◽  
Unnatural Death ◽  
Survivors Of Suicide ◽  
Self Image ◽  
Grief Process ◽  
Starting Point ◽  
Theoretical Considerations

The empirical studies on mourning after suicide were evaluated systematically with the aid of a descriptive model of grief. The starting point in the formulation of this model is the assumption that the bereaved are active in their processing of the loss. The current stages and component theories are rejected on the grounds of empirical contra-evidence and theoretical considerations. Instead, a framework of tasks of bereavement is presented in which the essential tasks confronting survivors in their adaption to the loss are formulated: detachment of the deceased, preserving a satisfactory self-image, and keeping in contact with people who can be of support during the grief process. An examination is made of what is known about the situation of survivors of suicide in this respect. Grief after suicide appears to differ on a number of qualitative aspects from grief after other causes of death. These differences probably do not, however, lead to an atypical mourning process. Generally speaking, the grief process seems to show the same course and main features as those occurring after other types of death, especially after sudden unnatural death. It can be concluded from the literature reviewed that there is no empirical evidence to support the popular notion that survivors of suicide show more pathological reactions, a more complicated and prolonged grief process, than other survivor groups.

scholarly journals Immunofluorescent microscopy in patients with IgA nephropathy

2019 ◽  
Vol 16 (3) ◽  
pp. 317-323
Author(s):  
K. S. Komissarov ◽  
M. V. Dmitrieva ◽  
T. A. Letkovskaya ◽  
V. S. Pilotovich ◽  
O. V. Krasko
Keyword(s):  
Gradual Increase ◽  
Pathological Findings ◽  
Positive Relation ◽  
Oxford Classification ◽  
Exclusion Criteria ◽  
Negative Relation ◽  
Endothelial Proliferation ◽  
The Oxford Classification ◽  
Acute Reaction ◽  
Igm Deposits

The aim of the study was to evaluate relations between the deposition of IgA, IgG, IgM, C3, C1q and baseline clinical features and pathological findings.According to exclusion criteria, 72 patients with diagnosed primary IgAN who were biopsied from 2015 to 2017 in the district of the Minsk city, Belarus were included for retrospective analysis. All biopsy had to be reviewed according to the Oxford classification (MEST-C). We examined the immunofluorescence staining with antibodies against IgG, IgA, IgM, C3, C1q.Mean age was 32 (26; 42.5) years, 72.2% was men, 48.6% of the patients had arterial hypertension. Median of proteinuria was 870 (355; 1420) mg/day, 8.4% of the patients had isolated hematuria, serum creatinine – 104 (89; 126.5) µmol/l.The patients with 3+ IgA deposits showed a significantly higher percentage of crescents (C1-2) than those with 2+ IgA deposits (p = 0.028). The presence of C3 deposits showed a gradual increase in the percentage of endothelial proliferation (E1) (p = 0.007). The degree of IgA deposits showed a significant negative relation to the IgM deposits (p = 0.01) and a positive relation to the C3 deposits (p = 0.001).We found that the intensity of IgA and C3 deposits is associated with histopathology markers of the acute reaction (C1-2 and E1) according to the Oxford classification. At the same time, the appearance of the IgM deposits testifies the acute phase of the disease as well as the advanced sclerotic stage in some patients.

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