Parameter Instability in Models of Local Unemployment Responses

1982 ◽  
Vol 14 (1) ◽  
pp. 75-94 ◽  
Author(s):  
R Dunn
Keyword(s):  
Spatial Pattern ◽  
Statistical Tests ◽  
Moving Window ◽  
Parameter Instability ◽  
Regional Unemployment ◽  
Local Areas ◽  
Over Time

Following papers by Brechling and Thirlwall, a number of studies have investigated the response of local or regional unemployment series to changes in the national series by means of regression approaches. In this paper a number of statistical tests for regression instability over time are discussed, and then applied to the Brechling model of unemployment responses in thirtynine local areas in the Severnside region. The results suggest marked instability in the regression over time, and moving window regression is introduced to track changes in the values of parameters. The spatial pattern of changing unemployment responses across the region is presented and discussed.

Belief Movement, Uncertainty Reduction, and Rational Updating*

2021 ◽  
Author(s):  
Ned Augenblick ◽  
Matthew Rabin
Keyword(s):  
Statistical Tests ◽  
Uncertainty Reduction ◽  
The State ◽  
Data Sets ◽  
New Information ◽  
The World ◽  
Core Concepts ◽  
Market Beliefs ◽  
Over Time

Abstract When a Bayesian learns new information and changes her beliefs, she must on average become concomitantly more certain about the state of the world. Consequently, it is rare for a Bayesian to frequently shift beliefs substantially while remaining relatively uncertain, or, conversely, become very confident with relatively little belief movement. We formalize this intuition by developing specific measures of movement and uncertainty reduction given a Bayesian’s changing beliefs over time, showing that these measures are equal in expectation and creating consequent statistical tests for Bayesianess. We then show connections between these two core concepts and four common psychological biases, suggesting that the test might be particularly good at detecting these biases. We provide support for this conclusion by simulating the performance of our test and other martingale tests. Finally, we apply our test to data sets of individual, algorithmic, and market beliefs.

scholarly journals Understanding Rockburst-Generating Behaviors and Associated Seismicity by Using a Spatial Calculation Methodology with an Energy Density Index

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Guifeng Wang ◽  
Xiaoyuan Yuan ◽  
Siyuan Gong ◽  
Linming Dou ◽  
Wu Cai ◽  
...  
Keyword(s):  
Energy Density ◽  
Rockburst Hazard ◽  
Density Index ◽  
Local Areas ◽  
Calculation Methodology ◽  
Coal Rock ◽  
Trends Over Time ◽  
Strong Tremors ◽  
The Relationship ◽  
Over Time

Rockbursts have become one of the most severe risks in underground coal mining. A proper understanding of the relationship between the spatial activities of mining-induced tremors and the occurrence of rockbursts can provide effective insight into the evaluation of rockburst hazard as well as revealing their causes. A methodology for spatially calculating the seismicity involving the use of an energy density index was developed to identify the evolution of mining-induced tremors over time. The results showed that numerous tremors occurred during the excavation and mining periods, and those tremors were distributed in a spatially complicated fashion, and it was difficult to identify their evolution trends over time and assess the rockburst hazard. However, energy density clouds had obvious distinguishable trends that presented nucleation characteristics and followed obvious extension around the nucleuses until strong tremors took place nearby. Velocity tomograms indicated that evolution of energy density clouds was the response to the rising stress concentration in some local areas before the rockburst. Then the rockburst-generating journey was inferred; that is, the jump of stress in local areas of coal-rock masses results in the clustering and nucleation of microfractures firstly, and then as the microfractures developed, macrofractures appeared, bringing strong tremors which triggered the rockburst.

scholarly journals DYNAMIC MATHEMATICAL MODEL OF URBAN SPATIAL PATTERN (RESIDENTIAL CHOICE OF LOCATION): MOBILITY VS EXTERNALITY

2015 ◽  
Vol 9 (1) ◽  
pp. 66-72
Author(s):  
Rahma Fitriani ◽  
Darmanto Darmanto
Keyword(s):  
Spatial Pattern ◽  
Inflation Rate ◽  
Urban Expansion ◽  
Optimal Solution ◽  
Static Model ◽  
Rate Of Change ◽  
Development Pattern ◽  
Residential Choice ◽  
Dynamic Version ◽  
Over Time

Household’s residential choice of location determines urban spatial pattern (e.g sprawl). The static model which assumes that the choice has been affected by distance to the CBD and location specific externality, fails to capture the evoution of the pattern over time. Therefore this study proposes a dynamic version of the model. It analyses the effects of externalities on the optimal solution of development decision as function of time. It also derives the effect of mobility and externality on the rate of change of development pattern through time. When the increasing rate of utility is not as significant as the increasing rate of income, the externalities will delay the change of urban spatial pattern over time. If the mobility costs increase by large amount relative to the increase of income and inflation rate, then the mobility effect dominates the effects of externalities in delaying the urban expansion.

scholarly journals Trend Analysis of Lakes and Sinkholes in Konya Closed Basin, Turkey

2021 ◽  
Author(s):  
Vahdettin DEMIR
Keyword(s):  
Trend Analysis ◽  
Flood Control ◽  
Statistical Tests ◽  
Water Levels ◽  
Trend Test ◽  
Lake Levels ◽  
Closed Basin ◽  
Thiessen Polygons ◽  
Over Time

Abstract Determining changes in the water level of lakes is essential in terms of flood control, water resource management, economic development, water-supply planning sustainability, and the sustainability of the ecosystem. Trend analysis is one of the most commonly used tools for detecting changes in the hydrological time series such as lake levels, precipitation and temperature. Trend analyses of meteorological variables and groundwater levels (baseflow components) are crucial toward the assessment of long-term changes in lake levels. This study aims to investigate the trend of long-term change in lakes (Lake Tuz and Lake Beyşehir) and sinkholes (Timraş and Kızören) in the Konya Closed Basin in Turkey. Changes in these lakes and sinkholes were examined along with changes in precipitation and groundwater trends representing the climate in the region. With the assistance of Thiessen polygons, precipitation stations, which affect the lakes and sinkholes, were determined. Several statistical tests exist that help determine the significance of hydrological trends over time. These tests are divided into two categories: parametric and nonparametric. In this study, the non parametric Innovative Sen trend test, the Modified Mann–Kendall trend test, and the parametric Linear Trend test were used. As a result of the trend analysis, it was observed that the water levels of Kızören and Timraş sinkholes decreased over time, and the water levels of Tuz Gölü and Beyşehir lakes increased over time. These results are supported by the trends of precipitation data and groundwater level data of the stations determined by the Thiessen polygons and sub-basin boundaries.

scholarly journals Effect of injection of botulinum toxin on decreasing the symptoms and signs of masticatory muscles in patients with temporomandibular dysfunction

2019 ◽  
Vol 13 (2) ◽  
pp. 128-132
Author(s):  
Mohammad Ali Ghavimi ◽  
Javad Yazdani ◽  
Atena Afzalimehr ◽  
Arezoo Ghoreyshizadeh ◽  
Seyed Vahid Dehnad
Keyword(s):  
Botulinum Toxin ◽  
Temporomandibular Joint ◽  
Statistical Tests ◽  
Mouth Opening ◽  
Masticatory Muscles ◽  
Pain Severity ◽  
Injection Technique ◽  
Invasive Treatment ◽  
Symptoms And Signs ◽  
Over Time

Background. Temporomandibular joint dysfunction (TMD) is a term that describes problems in the masticatory system, including the temporomandibular joint, the dento-muscular system and the supporting bones. Injection of botulinum toxin, as a noninvasive technique, might be useful in decreasing symptoms such as muscular spasm, dystonia, migraine headaches and TMD. Therefore, the aim of the present study was to evaluate the effect of injection of botulinum toxin on decreasing the symptoms and signs of masticatory muscles in patients with TMD. Methods. A total of 61 patients were consecutively included in the present study in 2016‒2017. All the subjects received a 50-unit injection of Dysport botulinum toxin in the masseter muscles using an extraoral injection technique. The results of the injection were evaluated in terms of pain severity using VAS, clinical evaluations of the joint click through palpation and by determining the inter-incisal distance. The patients underwent follow-up examinations at 1-week, 3-month and 6-month intervals after injection. Data were analyzed with appropriate statistical tests. Results. Comparison of pain severity and articular clicks at different intervals showed decreases in these parameters over time, with significant differences between the time intervals (P<0.05). Comparison of mouth opening at different intervals showed increases in mouth opening over time. Conclusion. The results of the present study showed that injection of botulinum toxin can be used in patients with TMD as a non-invasive treatment modality

scholarly journals Changes in precipitation rates over the last 70 years in Eastern Paraná State, Brazil

2021 ◽  
Vol 43 ◽  
pp. e15
Author(s):  
Bruno Henrique Toná Juliani ◽  
Cristhiane Michiko Passos Okawa ◽  
Miriam Rita Moro Mine
Keyword(s):  
Change Point ◽  
Abrupt Change ◽  
Historical Data ◽  
Statistical Tests ◽  
Positive Trend ◽  
Medium Term ◽  
Complete Series ◽  
Joseph Effect ◽  
Over Time

Temporal hydrometeorological series may present variations over time. The awareness of these characteristics is important to improve the monitoring of changes that these series may suffer along time. In this regard, the present paper aims to identify the existence of precipitation trends for the east portion of Paraná state, in Brazil, and also investigate the changes in the observed rates over the last 70 years. The statistical tests of Mann-Kendall and Pettitt, and also the Theil-Sen estimator, are applied for series of precipitation from 13 pluviometric stations of eastern Paraná state, Brazil, with 70 years of data records. By the results it was identified long-term linear positive trend for 11 of the precipitation series and also detected medium-term patterns in precipitation over 10 stations, characterizing the Joseph effect. These series have presented a behavior with higher rates in the most recent years in comparison from the first years of the historical data, sectioning the complete series into two shorter stationary periods, and presenting an abrupt change point.

scholarly journals Hydraulic characterization of porous pipes

2021 ◽  
Author(s):  
Yasmin Fernandes Silva ◽  
Luiz Antonio Lima ◽  
Michael Silveira Thebaldi ◽  
Virgílio Henrique Barros Nogueira ◽  
Adriano Valentim Diotto ◽  
...  
Keyword(s):  
Friction Factor ◽  
Statistical Tests ◽  
Head Loss ◽  
Multiple Comparison ◽  
Waste Generation ◽  
Anthropic Activity ◽  
Over Time

Abstract Increased anthropic activity in the environment leads to degradation and increased waste generation that includes tires, which can be used for the manufacture of porous pipes by extrusion for irrigation or aeration. There are no defined methodologies for the hydraulic characterization of porous pipes; in addition, their performance is questionable because the permeability of the wall in contact with water seems to decrease with time. Thus, this study aimed to perform the hydraulic characterization of porous pipes. Experiments were performed to assess the variation in permeability over time, the head loss, the friction factor, and the roughness. Statistical tests were performed to investigate possible significant differences between treatments. The results showed that the permeability varies over time and tends to decrease with each application of water. After a certain period, the permeability tends to become constant, and a stable flux can be determined, being the lowest average permeability and flux values found 0.591 × 10−15 m² 0.109 m³·m−2·s−1. There is variability in the permeability between pipe samples from the same batch as well as variability within the same sample, as indicated by the fact that some samples are similar to each other while others differ when performing a pairwise multiple comparison.

scholarly journals Acute and chronic physical activity improve spatial pattern separation in humans

2021 ◽  
Author(s):  
Daniela Ramirez Butavand ◽  
Maria Florencia Rodriguez ◽  
Maria Virginia Cifuentes ◽  
Magdalena Miranda ◽  
Cristian Garcia Bauza ◽  
...  
Keyword(s):  
Physical Activity ◽  
Spatial Pattern ◽  
Pattern Separation ◽  
Long Term Memory ◽  
Virtual Reality Environment ◽  
Spatial Memories ◽  
Spatial Pattern Separation ◽  
Sedentary Subjects ◽  
Over Time

Physical activity benefits both fitness and cognition. However, its effect on long-term memory is unclear. Successful memory involves not only remembering information over time but also keeping memories distinct and less confusing. The ability to separate similar experiences into distinct memories is one of the main features of episodic memory. In this work, we evaluated the effect of acute and chronic physical activity on a new task to assess spatial pattern separation in a 3D virtual reality environment. We manipulated the load of memory similarity and found that 25 minutes of cycling after encoding - but not before retrieval - was sufficient to improve similar, but not dissimilar memories, 24 hours after encoding. Furthermore, we found that participants who engaged in regular physical activity, but not sedentary subjects, showed memory for the similar condition the next day. Thus, physical activity could be a simple way to improve discrimination of spatial memories in humans.

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