scholarly journals A Simple Approach to Assess if a Financial “Bubble” is Present: The Case of Bitcoin

2019 ◽  
Vol 6 (4) ◽  
pp. 1
Author(s):  
Vitor M. A. da Fonseca ◽  
Manuel A. R. da Fonseca
Keyword(s):  
Statistical Tests ◽  
Efficient Market Hypothesis ◽  
Simple Approach ◽  
Stock Index ◽  
Regression Equations ◽  
Simple Method ◽  
Financial Bubble ◽  
Definition Of ◽  
Simple Regression ◽  
Statistical Definition

This article’s goal is to evaluate if the recent price behavior of Bitcoin can be characterized as a financial market “bubble”. To deal with this assessment, we adopt a statistical definition of a “bubble” derived from the efficient market hypothesis and we propose a simple method to test this proposition, based on the time-series model known as random walk. We analyze the data available for Bitcoin prices, together with an asset selected as benchmark, and perform statistical tests derived from simple regression equations. The main conclusion is that there is consistent evidence that that Bitcoin follows the pattern of a financial “bubble” – at least, such pattern is more evident in the case of Bitcoin than in the stock index used as benchmark.

UNCERTAINTY BASED ROBUST OPTIMIZATION IN AERODYNAMICS

2009 ◽  
Vol 23 (03) ◽  
pp. 477-480 ◽  
Author(s):  
ZHILI TANG
Keyword(s):  
Nash Equilibrium ◽  
Robust Design ◽  
Single Point ◽  
Optimization Method ◽  
Equilibrium Solutions ◽  
Design Problems ◽  
Nash Equilibrium Solutions ◽  
Definition Of ◽  
Taguchi Robust Design ◽  
Statistical Definition

The Taguchi robust design concept is combined with the multi-objective deterministic optimization method to overcome single point design problems in Aerodynamics. Starting from a statistical definition of stability, the method finds, Nash equilibrium solutions for performance and its stability simultaneously.

A Simple Approach to the Theory of Secondary Flows

1954 ◽  
Vol 5 (4) ◽  
pp. 218-234 ◽  
Author(s):  
J. H. Preston
Keyword(s):  
Simple Approach ◽  
Secondary Flows ◽  
Large Deflections ◽  
Simple Method ◽  
Vortex Sheets ◽  
Trailing Edges ◽  
Secondary Motion ◽  
Set Up ◽  
Uniform Stream

SummaryA simple method is developed for computing the trailing vorticity which arises when a non-uniform stream is turned.It is shown that, for a sudden and constant deflection of a non-uniform stream, no net trailing vorticity is set up in the exit flow and hence there is no secondary motion.In the case of an impulse cascade of finite dimensions with constant turning, it is found that the trailing vorticity has three distinct components—the passage vorticity and two components which appear as vortex sheets springing from the trailing edges of the aerofoils. It is shown that for small angles of deflection there is no net circulation associated with the trailing vorticity downstream, of the cascade, and it is inferred that this should still be so for large deflections.

The effect of level of environment on sex differences in pre-weaning growth rate in beef cattle

1977 ◽  
Vol 25 (1) ◽  
pp. 47-51 ◽  
Author(s):  
I. R. Hopkins
Keyword(s):  
Growth Rate ◽  
Sex Differences ◽  
Beef Cattle ◽  
Growth Rates ◽  
Additive Models ◽  
Regression Equations ◽  
Male And Female ◽  
Breed Differences ◽  
Per Se ◽  
Simple Regression

SUMMARYUsing pre-weaning records of 3822 calves from 11 Victorian herds, mean male and female growth rates and corresponding sex differences were calculated for each dam age and herd-year class. From these means simple regression equations relating sex differences and growth rates were calculated. There was a close similarity between equations based on dam age means and those based on herd-year means while correlations between sex differences and male growth rates were high.These results showed that sex differences and female growth rates could be predicted reliably from the level of environment as measured by male growth rate. Sex differences predicted by these regression relationships differed markedly from those predicted by the simple multiplicative and simple additive models generally used in adjusting for sex differences in selection.The results also suggested that other differences such as breed differences may be predictable in the same way and that such differences are determined primarily by the level of environment per se rather than differences in the nature of the components contributing to that level.

Isotaphonomy in concept and practice: an exploration of vertebrate microfossil bonebeds in the Upper Cretaceous (Campanian) Judith River Formation, north-central Montana

Paleobiology ◽  
2017 ◽  
Vol 43 (2) ◽  
pp. 248-273 ◽  
Author(s):  
Raymond R. Rogers ◽  
Matthew T. Carrano ◽  
Kristina A. Curry Rogers ◽  
Magaly Perez ◽  
Anik K. Regan
Keyword(s):  
Upper Cretaceous ◽  
Statistical Tests ◽  
Sampling Strategies ◽  
North Central ◽  
Wetland Ecosystems ◽  
Future Studies ◽  
Size And Shape ◽  
Definition Of ◽  
Central Montana ◽  
Judith River Formation

AbstractVertebrate microfossil bonebeds (VMBs)—localized concentrations of small resilient vertebrate hard parts—are commonly studied to recover otherwise rarely found small-bodied taxa, and to document relative taxonomic abundance and species richness in ancient vertebrate communities. Analyses of taphonomic comparability among VMBs have often found significant differences in size and shape distributions, and thus considered them to be non-isotaphonomic. Such outcomes of “strict” statistical tests of isotaphonomy suggest discouraging limits on the potential for broad, comparative paleoecological reconstruction using VMBs. Yet it is not surprising that sensitive statistical tests highlight variations among VMB sites, especially given the general lack of clarity with regard to the definition of “strict” isotaphonomic comparability. We rigorously sampled and compared six VMB localities representing two distinct paleoenvironments (channel and pond/lake) of the Upper Cretaceous Judith River Formation to evaluate biases related to sampling strategies and depositional context. Few defining distinctions in bioclast size and shape are evident in surface collections, and most site-to-site comparisons of sieved collections are indistinguishable (p≤0.003). These results provide a strong case for taphonomic equivalence among the majority of Judith River VMBs, and bode well for future studies of paleoecology, particularly in relation to investigations of faunal membership and community structure in Late Cretaceous wetland ecosystems. The taphonomic comparability of pond/lake and channel-hosted VMBs in the Judith River Formation is also consistent with a formative model that contends that channel-hosted VMBs were reworked from pre-existing pond/lake assemblages, and thus share taphonomic history.

scholarly journals Exploring price gap anomaly in the Ukrainian stock market

2019 ◽  
Vol 16 (2) ◽  
pp. 150-158 ◽  
Author(s):  
Alex Plastun ◽  
Inna Makarenko ◽  
Lyudmila Khomutenko ◽  
Svitlana Shcherbak ◽  
Olha Tryfonova
Keyword(s):  
Stock Market ◽  
Market Efficiency ◽  
Statistical Tests ◽  
Efficient Market Hypothesis ◽  
Trading Strategy ◽  
Momentum Effect ◽  
Dummy Variables ◽  
Price Patterns ◽  
Student’S T ◽  
Trading Simulation

This paper analyzes price gaps in the Ukrainian stock market for the case of UX index over the period 2009–2018. Using different statistical tests (Student’s t-tests, ANOVA, Mann-Whitney test) and regression analysis with dummy variables, as well as modified cumulative approach and trading simulation, the authors test a number of hypotheses searching for price patterns and abnormal market behavior related to price gaps: there is seasonality in price gaps (H1); price gaps generate statistical anomalies in the Ukrainian stock market (H2); upward gaps generate price patterns in the Ukrainian stock market (H3) and downward gaps generate price patterns in the Ukrainian stock market (H4). Overall results are consistent with the Efficient Market Hypothesis: there is no seasonality in price gaps and in most cases there is no evidences of price patterns or abnormal price behavior after the gaps in the Ukrainian stock market. Nevertheless, the authors find very strong and convincing evidences in favor of momentum effect on the days of negative gaps. These observations are confirmed by trading simulations: trading strategy based on detected price pattern generates profits and demonstrates overall efficiency, which is against the market efficiency. These results can be interesting both for academicians (further evidences against market efficiency) and practitioners (real and effective trading strategy to generate profits in the Ukrainian market market).

scholarly journals Microbial soil characteristics of grassland and arable soils linked to thermogravimetry data: correlations, use and limits

2021 ◽  
Author(s):  
Helena Doležalová-Weissmannová ◽  
Stanislav Malý ◽  
Martin Brtnický ◽  
Jiří Holátko ◽  
Michael Scott Demyan ◽  
...  
Keyword(s):  
Soil Properties ◽  
Soil Parameters ◽  
Organic Carbon Content ◽  
Regression Equations ◽  
Arable Soils ◽  
Grassland Soils ◽  
Simple Method ◽  
Organic C ◽  
Mass Losses ◽  
C And N

Abstract. Thermogravimetry (TG) is a simple method that enables rapid analysis of soil properties such as the content of total organic C, nitrogen, clay and C fractions with different stability. However, the possible link between TG data and microbiological soil properties has not been systematically tested yet and limits TG application for soil and soil organic matter assessment. This work aimed to search and to validate relationships of thermal mass losses (TML) to total C and N contents, microbial biomass C and N, basal and substrate-induced respiration, extractable organic carbon content, anaerobic ammonification, urease activity, short-term nitrification activity, specific growth rate, and time to reach the maximum respiration rate for two sample sets of arable and grassland soils. Analyses of the training soil set revealed significant correlations of TML with basic soil properties such as carbon and nitrogen content with distinguishing linear regression parameters and temperatures of correlating mass losses for arable and grassland soils. In a second stage the equations of significant correlations were used for validation with an independent second sample set. This confirmed applicability of developed equations for prediction of microbiological properties mainly for arable soils. For grassland soils was the applicability lower, which was explained as the influence of rhizosphere processes. Nevertheless, the application of TG can facilitate the understanding of changes in soil caused by microorganism’s activity and the different regression equations between TG and soil parameters reflect changes in proportions between soil components caused by land use management.

PENGARUH LABEL HALAL TERHADAP KEPUTUSAN MASYARAKAT MEMBELI PRODUK MAKANAN DAN MINUMAN (Studi Kasus Lingkungan VI Kelurahan Nangka Binjai Utara)

2020 ◽  
Vol 5 (2) ◽  
pp. 354
Author(s):  
Raja Sakti Putra Harahap
Keyword(s):  
Regression Model ◽  
Quantitative Method ◽  
Statistical Tests ◽  
A Value ◽  
Regression Formula ◽  
Simple Regression Model ◽  
Food And Beverage ◽  
R Value ◽  
Positive Effect ◽  
Simple Regression

This study aims to determine how the effect of the halal label on people’s decisions to buy food and beverage products. The method used is a quantitative method with a simple regression model and using statistical tests with the help of IBM SPSS Statistics 22 for windows. The sample in this study is the neighborhood community VI Nangka Village as many as 70 respondents. The results showed that the calculated r value was 0,79, so it could be saidthat there was s relationship or correlation between the variables X (Halal Label) with the variable Y ( The decision to buy food and beverage products). Then the t value < t table, which has a value of 0,657 < 1,668. Then  is accepted and  is rejected, which means that partially (X) variable does not have a significant effect on variable (Y), where the results of the hypothesis are accepted and proven after being calculated using a simple regression formula, namely Y = 34,7 + 0,67X.  By having a regression coefficoent of 0,675%, so the halal label has a positive effect on decisions to buy food and beverage products.

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