Point Estimation from a Decision-Theoretic Viewpoint

2010 ◽  
pp. 1-13
Author(s):  
Francisco J. Samaniego
Keyword(s):  
Point Estimation

scholarly journals Inference for the Exponential Distribution under Generalized Progressively Hybrid Censored Data from Partially Accelerated Life Tests with a Time Transformation Function

Mathematics ◽  
2021 ◽  
Vol 9 (13) ◽  
pp. 1510
Author(s):  
Alaa H. Abdel-Hamid ◽  
Atef F. Hashem
Keyword(s):  
Exponential Distribution ◽  
Failure Rate ◽  
Censored Data ◽  
Sufficient Conditions ◽  
Transformation Function ◽  
Point Estimation ◽  
Estimation Methods ◽  
Time Transformation ◽  
Monte Carlo Simulation Study ◽  
Accelerated Life

In this article, the tampered failure rate model is used in partially accelerated life testing. A non-decreasing time function, often called a ‘‘time transformation function", is proposed to tamper the failure rate under design conditions. Different types of the proposed function, which have sufficient conditions in order to be accelerating functions, are investigated. A baseline failure rate of the exponential distribution is considered. Some point estimation methods, as well as approximate confidence intervals, for the parameters involved are discussed based on generalized progressively hybrid censored data. The determination of the optimal stress change time is discussed under two different criteria of optimality. A real dataset is employed to explain the theoretical outcomes discussed in this article. Finally, a Monte Carlo simulation study is carried out to examine the performance of the estimation methods and the optimality criteria.

Even-Point Estimation

2014 ◽  
Author(s):  
Adrienne W. Kemp ◽  
C. David Kemp
Keyword(s):  
Point Estimation

scholarly journals POS0997 PERFORMANCE OF ASDAS VERSUS BASDAI DURING PREGNANCY

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 767.1-767
Author(s):  
P. Fischer ◽  
A. Zbinden ◽  
F. Foerger
Keyword(s):  
Disease Activity ◽  
Pregnant Women ◽  
Global Assessment ◽  
Signs And Symptoms ◽  
First Trimester ◽  
Point Estimation ◽  
High Disease Activity ◽  
Physician Global Assessment ◽  
Pregnancy And Postpartum ◽  
Pregnant State

Background:Disease activity in patients with axial spondyloarthritis (axSpA) can be measured by BASDAI and ASDAS. Both instruments were validated in non-pregnant patients with cutoff values for active diseases. In pregnant women with axSpA, however, BASDAI and ASDAS scores might be biased by signs and symptoms of pregnancy itself.Objectives:To compare the performance of ASDAS and BASDAI during pregnancyMethods:Patients with axSpA were prospectively followed before pregnancy, at each trimester and 6 to 12 weeks postpartum. Disease activity was assessed by BASDAI, ASDAS, patient global assessment (PGA) and physician global assessment (PhGA). We analysed the disease course throughout pregnancy and postpartum, the correlation between BASDAI and ASDAS and the agreement in the classification of active disease. We applied receiver operating curves (ROC) to evaluate the cut-off points in pregnant patients.Results:The study involved 40 women with axSpA. Disease activity scores were higher during pregnancy (median ASDAS score: 2.5, median BASDAI score 3.1) than during a non-pregnant state (median ASDAS score 2.3, median BASDAI score 2.1). Median BASDAI scores were highest at the first trimester, median ASDAS scores were highest at the second trimester. ASDAS strongly correlated with BASDAI, both in the pregnant and in the non-pregnant state (r=0.796, r=0.727). However, there was a discordance when analysing the proportion of patients with high disease activity using the common cut-off values (ASDAS >2.1, BASDAS >4). More patients had high disease activity when measured by ASDAS (1st trimester (T): 63%, 2nd T: 76%, 3rd T: 61%) compared to those measured by BASDAI (1st T 43%, 2nd T: 39%, 3rd T: 34%). The κ coefficient showed only fair agreement (κ=0.39). ROC analysis among pregnant patients showed that the cut-off point estimation for high disease activity using ASDAS >2.75 corresponded to a BASDAI >4. The ASDAS >2.75 cut-off for high disease activity had a good agreement with BASDAI >4 (κ=0.657). When ASDAS >2.75 was applied in pregnant women with axSpA, about 40% experienced high disease activity.Conclusion:During pregnancy, the majority of women with axSpA experience ongoing disease activity. However, the cut-off values defining low and high disease activity might differ between pregnant and non-pregnant individuals since BASDAI and ASDAS are biased by pregnancy related symptoms like fatigue and mechanical back pain.Disclosure of Interests:None declared.

scholarly journals Distress Regulates Different Pathways in the Brain of Common Carp: A Preliminary Study

Animals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 585
Author(s):  
Alexander Burren ◽  
Constanze Pietsch
Keyword(s):  
Gene Regulation ◽  
Common Carp ◽  
Binding Protein ◽  
Principal Component ◽  
Brain Regions ◽  
Point Estimation ◽  
Early Gene ◽  
Important Species ◽  
Preliminary Study ◽  
The Brain

In this study, a stress trial was conducted with common carp, one of the most important species in aquaculture worldwide, to identify relevant gene regulation pathways in different areas of the brain. Acute distress due to exposure to air significantly activated the expression of the immediate early gene c-fos in the telencephalon. In addition, evidence for regulation of the two corticotropin-releasing factor (crf) genes in relation to their binding protein (corticotropin-releasing hormone-binding protein, crh-bp) is presented in this preliminary study. Inferences on the effects of due to exposure to air were obtained by using point estimation, which allows the prediction of a single value. This constitutes the best description to date of the previously generally unknown effects of stress in different brain regions in carp. Furthermore, principal component analyses were performed to reveal possible regulation patterns in the different regions of the fish brain. In conclusion, these preliminary studies on gene regulation in the carp brain that has been influenced by exposure to a stressor reveal that a number of genes may be successfully used as markers for exposure to unfavourable conditions.

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