Comparison of Distance Estimates for Commodity Flow Survey: Great Circle Distances Versus Network-Based Distances

2002 ◽  
Vol 1804 (1) ◽  
pp. 212-216 ◽  
Author(s):  
Mohammad A. Qureshi ◽  
Ho-Ling Hwang ◽  
Shih-Miao Chin
Keyword(s):  
Great Circle ◽  
Statistical Bias ◽  
Commodity Flow ◽  
Oak Ridge ◽  
National Highway ◽  
Highway Network ◽  
Unbiased Estimates ◽  
The Mean ◽  
Zip Code ◽  
Distance Category

A study was conducted to compare distance estimates derived from great circle distances (GCD) with distance estimates derived from a network-based model. The study used a sample of shipments from the 1993 commodity flow survey (CFS). For each shipment in the sample, the distance from the zip code of origin to the zip code of destination was calculated by using the Oak Ridge National Laboratories National Highway Network and assuming that the minimum impedance path was utilized. For each of these origin–destination pairs, the GCD and several variations of the GCD also were estimated. Finally, the network-based estimates and the GCD-based estimates were statistically compared. As expected, distance estimates based on GCD were found to be different from network-based estimates. However, applying a constant circuity factor of 1.22 or using variable circuity factors based on distance category did not result in a statistical bias in these distance estimates. Examination of distance estimates at the level of origin–destination pair revealed that distance estimates could vary as much as 75%. A comparison of published values for the 1997 CFS with values derived from GCD-based distance estimates shows that approximately 5% to 35% of the GCD-based values for the 1997 CFS would fall outside a two standard error interval. Although GCD-based estimates, under some conditions, may produce unbiased estimates of the mean distance, this does not eliminate the need for network-based estimates.

Zip Code-Related Income Disparities in Patients with Colorectal Cancer

2021 ◽  
pp. 000313482110234
Author(s):  
Yasmeen Z. Qwaider ◽  
Naomi M. Sell ◽  
Chloe Boudreau ◽  
Caitlin E. Stafford ◽  
Rocco Ricciardi ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Income Group ◽  
Tertiary Hospital ◽  
Lower Proportion ◽  
Stage Iii ◽  
Median Income ◽  
Lower Income ◽  
Income Disparities ◽  
The Mean ◽  
Zip Code

Introduction Screening and early detection reduce morbidity and mortality in colorectal cancer. Our aim is to study the effect of income disparities on the clinical characteristics of patients with colorectal cancer in Massachusetts. Methods Patients were extracted from a database containing all surgically treated colorectal cancers between 2004 and 2015 at a tertiary hospital in Massachusetts. We split patients into 2 groups: “above-median income” and “below-median income” according to the median income of Massachusetts ($74,167). Results The analysis included 817 patients. The above-median income group consisted of 528 patients (65%) and the below-median income group consisted of 289 patients (35%). The mean age of presentation was 64 ± 15 years for the above-median income group and 67 ± 15 years for the below-median income group ( P = .04). Patients with below-median income were screened less often ( P < .001) and presented more frequently with metastatic disease ( P = .02). Patients with above-median income survived an estimated 15 months longer than those with below-median income ( P < .001). The survival distribution was statistically significantly different between the groups for stage III disease ( P = .004), but not stages I, II, or IV ( P = 1, 1, and .2, respectively). For stage III disease, a lower proportion of below-median income patients received chemotherapy (61% vs. 79%, P = .002) and a higher proportion underwent nonelective surgery (5% vs. 2%, P = .007). Conclusions In Massachusetts, patients with colorectal cancer residing in lower income areas are screened less, received adjuvant chemotherapy less, and have worse outcomes, especially when analyzing those who present with stage III disease.

Statistical Bias Problem in On-Site Surveys: the Severity of the Problem and its Potential for Solution

1975 ◽  
Vol 32 (12) ◽  
pp. 2520-2524
Author(s):  
William F. Sinclair ◽  
R. W. Morley
Keyword(s):  
Fishing Effort ◽  
Recreational Fisheries ◽  
Statistical Bias ◽  
Relative Probability ◽  
Fishing Vessels ◽  
Frequency Of Use ◽  
Unbiased Estimates ◽  
Weighting Procedures ◽  
Use Category

Commercial and recreational fisheries managers often develop catch and effort estimates from information gathered in location or on-site surveys. However, a limited on-site sample cannot produce unbiased estimates of fishing effort or socioeconomic traits of the anglers unless weighting procedures are adopted to account for the varying frequencies of fishing of the fishermen. The corrective procedure involves establishing the relative probability of capturing a fisherman in the sample, then weighting the number of contacts with anglers in each frequency of use category. Unless information on the probability of including particular fishermen and fishing vessels in the sample is available the sample must be drawn with replacement.

Trans-Canada Slimeways

2014 ◽  
pp. 251-265
Author(s):  
Andrew Adamatzky ◽  
Selim G. Akl
Keyword(s):  
Urban Areas ◽  
Physarum Polycephalum ◽  
Minimum Energy ◽  
Extended Body ◽  
Slime Mould ◽  
Proximity Graphs ◽  
Maximum Coverage ◽  
National Highway ◽  
Highway Network ◽  
Similarities And Differences

Slime mould Physarum polycephalum builds up sophisticated networks to transport nutrients between distant parts of its extended body. The slime mould’s protoplasmic network is optimised for maximum coverage of nutrients yet minimum energy spent on transportation of the intra-cellular material. In laboratory experiments with P. polycephalum we represent Canadian major urban areas with rolled oats and inoculated slime mould in the Toronto area. The plasmodium spans the urban areas with its network of protoplasmic tubes. The authors uncover similarities and differences between the protoplasmic network and the Canadian national highway network, analyse the networks in terms of proximity graphs and evaluate slime mould’s network response to contamination.

EFFECTS OF FLIGHT ROUTE VARIATION AND GREAT-CIRCLE APPROXIMATION ON AVIATION DOSE ASSESSMENT FOR POPULAR FLIGHTS FROM TAIWAN

2018 ◽  
Vol 184 (1) ◽  
pp. 79-89 ◽  
Author(s):  
Zi-Yi Yang ◽  
Rong-Jiun Sheu
Keyword(s):  
Cosmic Ray ◽  
Mean Value ◽  
Great Circle ◽  
Dose Assessment ◽  
Tracking Data ◽  
Secondary Particles ◽  
The Mean ◽  
Flight Route ◽  
Airline Crews ◽  
Galactic Cosmic Ray

Abstract Galactic cosmic-ray-induced secondary particles in the atmosphere constitute an important source of radiation exposure to airline crews and passengers. In this study, a systematic dose assessment was conducted for 11 popular flights from Taiwan, with an emphasis on the effects of flight route variation and assumption. The case studies covered a broad range of commercial flights departing from Taipei, from a domestic flight of <1 h to a long-haul international flight of more than 14 h. For each route under study, information on 100 actual flight routes was retrieved from flight tracking data collected from June to September 2017, and the information was analyzed using a self-developed program called the ‘NTHU Flight Dose Calculator’. The resulting distribution of route doses provided not only the mean value and associated standard deviation but also information on the characteristics of aviation dose assessment and management. Furthermore, compared with actual flight routes, the dose differences introduced by great-circle approximation were evaluated, and the effects of solar activity on the dose assessment of these flights were reported.

scholarly journals Comparison of estimators in one-phase two-stage Poisson sampling in forest inventories

2012 ◽  
Vol 42 (10) ◽  
pp. 1865-1871 ◽  
Author(s):  
Daniel Mandallaz ◽  
Alexander Massey
Keyword(s):  
Small Area ◽  
Two Stage ◽  
Random Sample Size ◽  
Poisson Sampling ◽  
Second Stage ◽  
Forest Inventories ◽  
Unbiased Estimates ◽  
The Mean ◽  
Concentric Circles ◽  
Better Than

In the context of Poisson sampling, numerous adjustments to classical estimators have been proposed that are intended to compensate for inflated variance due to random sample size. However, such adjustments have never been applied to extensive forest inventories. This work investigates the performances of four estimators for the timber volume in one-phase two-stage forest inventories, where trees in the first stage are selected, at the plot level, by concentric circles or angle-count methods and a subset thereof are selected by Poisson sampling for further measurements to get a better estimation. The original two-stage estimator is the sum of two components: the first is the mean of Horwitz–Thompson estimators using simple volume approximations, based on diameter and species alone, of all first-stage trees in each inventory plot, and the second is the mean of Horwitz–Thompson estimators based on the differences between the simple volume approximations and refined volume determinations based on further diameter and height measurements on the second-stage trees within each inventory plot. This two-stage estimator is particularly useful because it provides unbiased estimates even if the simple prediction model is not correct, which is particularly important for small area estimation. The other three estimators rely on adjustments of the second component of the original estimator that are adapted from estimators proposed in the literature by L.R. Grosenbaugh and C.-E. Särndal. It turns out that these adjustments introduce a negligible bias and that the original simple estimator performs just as well or even better than the new estimators with respect to the variance.

network scale-up method

2004 ◽  
Vol 1 (2) ◽  
pp. 395-405
Author(s):  
Silvia Snidero ◽  
Roberto Corradetti ◽  
Dario Gregori
Keyword(s):  
Social Network ◽  
Scale Up ◽  
Monte Carlo Simulation Study ◽  
The Social ◽  
Network Scale ◽  
Ideal Number ◽  
Unbiased Estimates ◽  
The Mean ◽  
Ml Estimator ◽  
Biased Estimates

The network scale-up method is a social network estimator for the size of hidden or hard-to-count subpopulations. These estimators are based on a simple model which have however strong assumptions. The basic idea is that the proportion of the mean number of people known by respondent in a subpopulation E of T of size e is the same of the proportion that the e subpopulation E forms in general population T of size t: mc = t , where c is the number of persons known by each respondent and m is the mean number of persons known by each respondent in the subpopulation E. The persons known by every subject is called the "social network", and its size is c, estimated by several estimators proposed in the recent literature. In this paper we present a Monte Carlo simulation study aimed at understanding the behavior of the scale-up method type estimators under several conditions. The first goal was to understand what would be the ideal number of subpopulations of known size to be used in planning the research. The second goal was to analyze what happens when we use overlapped subpopulations. Our results showed that with the scale-up estimator we always obtain biased estimates for any number of subpopulations employed in estimates. With the Killworth's ML estimator, the improvement of scale-up method, we have substantially unbiased estimates under any condition. Also in case of overlapping, and increasing the degree of it among subpopulations, bias raises with scale-up method, instead it remains close to zero with ML estimator.

scholarly journals Donor Socioeconomic Status As a Predictor of Altered Immune Function and Treatment Response Following Hematopoietic Cell Transplantation for Hematologic Malignancy

Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 843-843
Author(s):  
Lucie M Turcotte ◽  
Tao Wang ◽  
Kirsten M Beyer ◽  
Steve W Cole ◽  
Stephen R. Spellman ◽  
...  
Keyword(s):  
Socioeconomic Status ◽  
Stem Cell ◽  
Hematopoietic Cell Transplantation ◽  
Hematologic Malignancy ◽  
Advisory Board ◽  
Socioeconomic Disadvantage ◽  
Hematopoietic Cell ◽  
Composite Score ◽  
The Mean ◽  
Zip Code

Abstract Introduction: Hematopoietic cell transplantation (HCT) carries significant risks for mortality, which are not proportionally shared across individuals. Among HCT recipients, we have previously shown that low socioeconomic status (SES) is predictive of increased mortality following HCT, and the underlying mechanism for this outcome is not fully explained by race, insurance status or access to care. Furthermore, following HCT, the donor immune system replaces that of the recipient, leading to long-term engraftment with donor-derived immune cells. Previous work has not addressed the influence of donor socioeconomic factors on HCT recipient outcomes. Therefore, we hypothesized that SES would impact donor hematopoietic cells and this effect would be transferrable and associated with adverse recipient outcomes. Methods: Recipients of matched unrelated donor allogeneic peripheral blood stem cell HCT between 2000-2013 for hematologic malignancy, resided in the United States (US) with a documented ZIP code, and had a HCT donor with documented US ZIP code were identified from the Center for International Blood and Marrow Transplantation Research (CIBMTR). Using donor ZIP code, SES measures of household income, poverty, education, housing and employment were derived from the U.S. Census American Community Survey. A standardized donor SES composite score was computed as an equally weighted average of the 5 standardized SES variables (mean composite score = 0, standard deviation (SD) = 1). Multivariable models, adjusted for donor and recipient characteristics, were used to evaluate associations between donor SES composite score with HCT recipient disease free survival (DFS), overall survival (OS), treatment related mortality (TRM), relapse, and acute and chronic graft versus host disease (GVHD). Results were considered significant if P &lt; 0.01. Results: Among 2,005 HCT recipients, median age at diagnosis was 51 years (range 1-77), 44% were female, and 55% had acute myeloid leukemia. Median post-HCT follow up was 120 months (range 4-219). Donors were 44% female and median age at hematopoietic cell donation was 34.7 years (range 18-62). The standardized donor composite scores ranged from -2.6 to 3.9, with a higher composite score indicative of greater socioeconomic disadvantage. Multivariable analyses identified significant associations between the standardized donor SES composite score and DFS (HR 1.07 per SD SES, 95% CI 1.02-1.13; p=0.0088), OS (HR 1.09 per SD SES, 95% CI 1.04-1.15; p=0.0007), and TRM (HR 1.10 per SD SES, 95% CI 1.03-1.17; p=0.0049). Significant associations were not identified between donor SES and relapse or GVHD. Quantitatively, recipients transplanted with cells from a donor of greater socioeconomic disadvantage (i.e. SES composite score 2 SD above the mean) experienced a 10% reduction in DFS and OS, and a 5% increase in TRM at 3 years compared with those transplanted with cells from a high-SES donor (SES composite score 2 SD below the mean) (Figure). Conclusions: For the first time, we have demonstrated that socioeconomic disadvantage among HCT donors results in adverse transplant outcomes in the HCT recipient. This novel finding suggests that SES has biologic impacts down to the stem cell level that persist even when transplanted into a new host during HCT. The implications of these findings are broad and suggest the need for public health interventions targeting socioeconomic support as a means for preventing social disparities in cancer treatment outcomes. Figure 1 Figure 1. Disclosures Verneris: Novartis: Other: advisory board; jazz: Other: advisory board; Fate Therapeutics: Consultancy.

scholarly journals Estimation of genetic parameters in the analysis of square lattice experiment group

Bragantia ◽  
1999 ◽  
Vol 58 (1) ◽  
pp. 195-208
Author(s):  
JOSÉ MARCELO SORIANO VIANA ◽  
ADAIR JOSÉ REGAZZI
Keyword(s):  
Treatment Effect ◽  
Genetic Parameters ◽  
Square Lattice ◽  
Environment Effect ◽  
Environment Effects ◽  
Unbiased Estimates ◽  
The Mean ◽  
Covariance Components ◽  
Variance And Covariance Components ◽  
Selection Of

Aiming to demonstrate how to obtain unbiased estimates of genetic parameters of base populations, unaffected by genotype x environment effects, this paper presents the variance and covariance components of the intra-block analysis of a group of square lattice experiments and the estimators of the components associated to treatment effect. Random model and mixed models with environment effect fixed and other effects random are considered. In the analysis with treatments not corrected for blocks/replications/environments, the estimators of the variance and covariance components due to treatment effect are different from those of the analysis considering the complete block model. Data from two experiments of a breeding program of Eucalyptus pyrocarpa were used for genetic analysis. The analysis of variance of height and diameter indicated absence of interaction between progeny and environment. Due to this result, the prediction of the direct and indirect genetic gains was based on the mean of the two environments. The high estimates of narrow sense heritabilities and additive genetic correlation indicate that selection of the superior families will be effective in changing the means of the base population for both traits.

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