A territorial approach to firm entry: The effect of city size

This paper concerns the effects of territorial factors on the processes involved in the creation of manufacturing firms in Spanish cities. Most contributions have focused on regional factors rather than urban ones. Here we assume that it is possible to identify certain urban factors that attract new firms. We use data for the entry of firms in Spanish manufacturing industries between 1994 and 2002. This paper contributes to the existing literature on market entry. Key words: cities, regions, firm entry and Spanish economy. JEL: R0, R12, L60

Effect of training-sample size and classification difficulty on the accuracy of genomic predictors.

Introduction: As part of the MicroArray Quality Control (MAQC)-II project, this analysis examines how the choice of univariate feature-selection methods and classification algorithms may influence the performance of genomic predictors under varying degrees of prediction difficulty represented by three clinically relevant endpoints. Methods: We used gene-expression data from 230 breast cancers (grouped into training and independent validation sets), and we examined 40 predictors (five univariate feature-selection methods combined with eight different classifiers) for each of the three endpoints. Their classification performance was estimated on the training set by using two different resampling methods and compared with the accuracy observed in the independent validation set. Results: A ranking of the three classification problems was obtained, and the performance of 120 models was estimated and assessed on an independent validation set. The bootstrapping estimates were closer to the validation performance than were the cross-validation estimates. The required sample size for each endpoint was estimated, and both gene-level and pathway-level analyses were performed on the obtained models. Conclusions: We showed that genomic predictor accuracy is determined largely by an interplay between sample size and classification difficulty. Variations on univariate feature-selection methods and choice of classification algorithm have only a modest impact on predictor performance, and several statistically equally good predictors can be developed for any given classification problem.

Measuring an effect size from dichotomized data : contrasted results whether using a correlation or an odds-ratio

It is well known that dichotomizing continuous data has the effect to decrease statistical power when the goal is to test for a statistical association between two variables. Modern researchers however are focusing not only on statistical significance but also on an estimation of the "effect size" (i.e., the strength of association between the variables) to judge whether a significant association is also clinically relevant. In this article, we are interested in the consequences of dichotomizing continuous data on the value of an effect size in some classical settings. It turns out that the conclusions will not be the same whether using a correlation or an odds ratio to summarize the strength of association between the variables: Whereas the value of a correlation is typically decreased by a factor pi/2 after each dichotomization, the value of an odds ratio is at the same time raised to the power 2. From a descriptive statistical point of view, it is thus not clear whether dichotomizing continuous data leads to a decrease or to an increase in the effect size, as illustrated using a data set to investigate the relationship between motor and intellectual functions in children and adolescents

Effective size of two feral domestic cat populations (Felis catus L): effect of the mating system.

A variety of behavioural traits have substantial effects on the gene dynamics and genetic structure of local populations. The mating system is a plastic trait that varies with environmental conditions in the domestic cat (Felis catus) allowing an intraspecific comparison of the impact of this feature on genetic characteristics of the population. To assess the potential effect of the heterogenity of males' contribution to the next generation on variance effective size, we applied the ecological approach of Nunney & Elam (1994) based upon a demographic and behavioural study, and the genetic 'temporal methods' of Waples (1989) and Berthier et al. (2002) using microsatellite markers. The two cat populations studied were nearly closed, similar in size and survival parameters, but differed in their mating system. Immigration appeared extremely restricted in both cases due to environmental and social constraints. As expected, the ratio of effective size to census number (Ne/N) was higher in the promiscuous cat population (harmonic mean = 42%) than in the polygynous one (33%), when Ne was calculated from the ecological method. Only the genetic results based on Waples' estimator were consistent with the ecological results, but failed to evidence an effect of the mating system. Results based on the estimation of Berthier et al. (2002) were extremely variable, with Ne sometimes exceeding census size. Such low reliability in the genetic results should retain attention for conservation purposes.

The effect of plantation silviculture on soil organic matter and particle-size fractions in Amazonia

Eucalyptus grandis and other clonal plantations cover about 3.5 million ha in Brazil. The impacts of intensively-managed short-rotation forestry on soil aggregate structure and Carbon (C) dynamics are largely undocumented in tropical ecosystems. Long-term sustainability of these systems is probably in part linked to maintenance of soil organic matter and good soil structure and aggregation, especially in areas with low-fertility soils. This study investigated soil aggregate dynamics on a clay soil and a sandy soil, each with a Eucalyptus plantation and an adjacent primary forest. Silvicultural management did not reduce total C stocks, and did not change soil bulk density. Aggregates of the managed soils did not decrease in mass as hypothesized, which indicates that soil cultivation in 6 year cycles did not cause large decreases in soil aggregation in either soil texture. Silt, clay, and C of the sandy plantation soil shifted to greater aggregate protection, which may represent a decrease in C availability. The organic matter in the clay plantation soil increased in the fractions considered less protected while this shift from C to structural forms considered more protected was not observed.

Effect of the Glenosphere Position and Size on Reverse Shoulder Prostheses Mobility

Introduction: Several methods have already been proposed to improve the mobility of reversed prostheses (lateral or inferior displacement, increase of the glenosphere size). However, the effect of these design changes have only been evaluated on the maximal range of motion and were not related to activities of daily living (ADL). Our aim was thus to measure the effect of these design changes and to relate it to 4 typical ADL. Methods: CT data were used to reconstruct a accurate geometric model of the scapula and humerus. The Aequalis reversed prosthesis (Tornier) was used. The mobility of a healthy shoulder was compared to the mobility of 4 different reversed designs: 36 and 42 mm glenospheres diameters, inferior (4 mm) and lateral (3.2 mm) glenospheres displacements. The complete mobility map of the prosthesis was compared to kinematics measurement on healthy subjects for 4 ADL: 1) hand to contra lateral shoulder, 2) hand to mouth, 3) combing hair, 4) hand to back pocket. The results are presented as percentage of the allowed movement of the prosthestic shouder relative to the healthy shoulder, considered as the control group. Results: None of the tested designs allowed to recover a full mobility. The differences of allowed range of motion among each prosthetic designs appeared mainly in two of the 4 movements: hand to back pocket and hand to contra lateral shoulder. For the hand to back pocket, the 36 had the lowest mobility range, particularly for the last third of the movement. The 42 appeared to be a good compromise for all ADL activities. Conclusion: Reverse shoulder prostheses does not allow to recover a full range of motion compared to healthy shoulders, even for ADL. The present study allowed to obtain a complete 3D mobility map for several glenosphere positions and sizes, and to relate it to typical ADL. We mainly observed an improved mobility with inferior displacement and increased glenosphere size. We would suggest to use larger glenosphere, whenever it is possible.

The Effect of Inoculum Size on Selection of In Vitro Resistance to Vancomycin, Daptomycin, and Linezolid in Methicillin-Resistant Staphylococcus aureus.

OBJECTIVES: The inoculum effect (IE) is an increase in the minimum inhibitory concentration (MIC) at high bacterial densities. The effect of three inoculum sizes on the selection of resistance to vancomycin, daptomycin, and linezolid was investigated in methicillin-resistant Staphylococcus aureus (MRSA). METHODS: Low (10(4) CFU/ml), medium (10(6) CFU/ml), and high (10(8) CFU/ml) inocula of MRSA were exposed to twofold increasing concentrations of either drug during 15 days of cycling. MICs for low (MICL), medium (MICM), and high (MICH) inocula were determined daily. Conventional MICs were measured at days 1, 5, 10, and 15. Experiments were performed in triplicate. RESULTS: At the beginning of the experiment a small IE was observed for vancomycin (MICL=1 μg/ml, MICM=1-2 μg/ml, and MICH=2 μg/ml) and a significant IE for daptomycin (MICL=0.25 μg/ml, MICM=0.25-0.5 μg/ml, and MICH=2 μg/ml). Linezolid exhibited no IE at low and medium inocula (MICL=1 μg/ml and MICM=1-2 μg/ml), but with the high inoculum, concentrations up to 2,048 μg/ml did not fully inhibit visual growth. During cycling, increase of MIC was observed for all antibiotics. At day 15, MICL, MICM, and MICH of vancomycin were 2-4, 4-8, and 4-16 μg/ml and of daptomycin were 0.5-2, 8-128, and 64-256 μg/ml, respectively. MICL and MICM of linezolid were 1 and 2-4 μg/ml, respectively. Conventional MICs showed vancomycin and daptomycin selection of resistance since day 5 depending on the inocula. No selection of linezolid resistance was observed. CONCLUSIONS: Our results showed the importance of the inoculum size in the development of resistance. Measures aimed at lowering the inoculum at the site of infection should be used whenever possible in parallel to antimicrobial therapy.

Comparing 'visual' effect size indices for single-case designs

Effect size indices are indispensable for carrying out meta-analyses and can also be seen as an alternative for making decisions about the effectiveness of a treatment in an individual applied study. The desirable features of the procedures for quantifying the magnitude of intervention effect include educational/clinical meaningfulness, calculus easiness, insensitivity to autocorrelation, low false alarm and low miss rates. Three effect size indices related to visual analysis are compared according to the aforementioned criteria. The comparison is made by means of data sets with known parameters: degree of serial dependence, presence or absence of general trend, changes in level and/or in slope. The percent of nonoverlapping data showed the highest discrimination between data sets with and without intervention effect. In cases when autocorrelation or trend is present, the percentage of data points exceeding the median may be a better option to quantify the effectiveness of a psychological treatment.

Effect of neighborhood and plot size on experiments with multiple-harvest oleraceous crops

The objective of this work was to determine the efficiency of the Papadakis method on the quality evaluation of experiments with multiple-harvest oleraceous crops, and on the estimate of the covariate and the ideal plot size. Data from nine uniformity trials (five with bean pod, two with zucchini, and two with sweet pepper) and from one experiment with treatments (with sweet pepper) were used. Through the uniformity trials, the best way to calculate the covariate was defined and the optimal plot size was calculated. In the experiment with treatments, analyses of variance and covariance were performed, in which the covariate was calculated by the Papadakis method, and experimental precision was evaluated based on four statistics. The use of analysis of covariance with the covariate obtained by the Papadakis method increases the quality of experiments with multiple-harvest oleraceous crops and allows the use of smaller plot sizes. The best covariate is the one that considers a neighboring plot of each side of the reference plot.

The effect of age at the first mating and herd size on the lifetime productivity of sows

The effect of age at the first mating and herd size were evaluated in the reference Spanish Databank (BDporc) of 37 698 sows born between 1991 and 1995 and with individual lifetime records. The data included dates of births at entrance and culling, first mating, repetitive mating and conception, first farrowing and weaning records. Individual records were validated before the analysis by screening them through a tolerance “filter” in order to eliminate the extreme values from the analysis. The total database of the sows was classified in 7 classes according to age at the first mating (< 210, 210–220, 221–230, 231–240, 241–250, 251–270, and > 270 days) and in 6 classes of herd size (< 200, 200–300, 301–400, 401–600, 601–800, and > 800 sows). The total number of litters and number of weaned piglets obtained from each sow during the lifetime production were significantly (P < 0.05) greater for gilts between 221 and 240 d of age at the first mating. There was a significant (P < 0.001) effect of the herd size on the reproductive performance of the sow, and the best performance was obtained with herds with 401 to 600 sows compared to < 200 or > 800 sow-herds. Furthermore, a significant (P < 0.001) interaction between age at the first mating and herd size was detected and can be associated with a particular pattern for the herd size class 401–600 sows with the best performances obtained for the sows first mated at less than 200 days. For the other herd sizes, the results indicated that sows mated for the first time at the right age, 221–240 days, are more productive, both in the number and size of the parities throughout lifetime production.