194,828 research outputs found
Exercise with R
No full textThese notes are a companion material to the course 'The R language and environment for statistical computing' held by the author at Università Cattolica del Sacro Cuore, Bachelor Degree in 'Economics and management'.
The aim of the course is to make participants able to implement statistical procedures in order to properly solve business and economic problems by means of the open source software R (R Core Team, 2019).
The reader is assumed to possess a basic understanding of statistics with regard to data analysis, probability and inference, at the level of the combined courses 'Statistica (Analisi dei dati e probabilità)'/Statistics and 'Statistica applicata'/'Applied statistics and big data' teached at Università Cattolica del Sacro Cuore.
Notes are organized as follows.
Sections from 1 to 3 consider the basics of R and deal with problems of descriptive statistics, according to the methodological presentation available e.g. in Boari, Cantaluppi (2018).
Section 4 considers the generation of pseudo-random numbers, introduces some simulation problems and gives the basics on how to work with parallel architectures.
Section 5 explains how to read/import data in R by also considering social network and open data sources.
Section 6 illustrates how to solve some basic mathematical problems. In particular, graphical representations of functions in one and two variables, optimization problems and solution to system of equations and system of inequalities are considered.
Section 7 proposes a short analysis of the survey on households wealth administered by the Bank of Italy (2014).
Section 8 describes how to solve some basic inferential problems (fitting distributions, testing population proportions, testing mean and variances in one and two sample instances, fitting linear and generalized linear (logit) models).
Finally, Appendix A gives a brief introduction to packages dplyr, ggplot2 and ggmap that are frequently used in data science applications.
Sections from 1 to 7 are accompanied by exercises. Verzani (2002), Wickman, Grolemund (2016) and Williams (2017) are useful references for further methods/exercises/problems.
Companion material to these notes (files, data sources and codes) can be requested to the author.
These notes were produced with R (version 3.5.3), knitr 1.22 and MiKTeX 2.9
R&D incentives: the effectiveness of a place-based policy
No full textThe empirical evidence concerning the impact of R&D subsidies on both sides of the innovation process (input and output) and the overall performance of the firm is mixed. Moreover, while the role of regions in implementing innovation policies has increased since the last decade, little is known on the effectiveness of regional policy. This paper analyzes the effectiveness of a local R&D policy implemented in the Italian province of Trento, during the period 2002-07. The econometric analysis is based on counterfactual models. We evaluate the achievements of the local policy maker with respect to the following objectives: (i) prompt additional investment in innovation; (ii) enhance the overall competitiveness of the business sector in the regional area. We find that R&D incentives positively affect investments in intangible assets and human capital, while they have no effect on firms’ turnover, labor productivity and profitability
R code associated with Methods for Implementing Integrated Step-Selection Functions with Incomplete Data
No full textSee Readme file uploaded with the repositoryThis repository contains R code (along with associated output from running the code) presented in: Hofmann, D. D., G. Cozzi, and J. Fieberg. Methods for Implementing Integrated Step-Selection Functions with Incomplete Data.Swiss National Science Foundation Grant No. 310030 204478National Aeronautics and Space Administration 496 award 80NSSC21K1182Hofmann, David D; Cozzi, Gabriele; Fieberg, John R. (2023). R code associated with Methods for Implementing Integrated Step-Selection Functions with Incomplete Data. Retrieved from the Data Repository for the University of Minnesota (DRUM), https://doi.org/10.13020/6wcd-6s43
« Degli amori. parte seconda. Gabriello Symeoni alle donne d'ingegno et più gentili salute » , P. 74 r°
No full textSimeoni Gabriele. « Degli amori. parte seconda. Gabriello Symeoni alle donne d'ingegno et più gentili salute » , P. 74 r° . In: Seizième Siècle, N°7, 2011. pp. 67-83
Shape optimization of shells: an R-Funicularity based approach
No full textShells with a funicular shape with respect to a given load should be able to bear it without introducing bending. Usually, this is not possible due to boundary conditions and bending stiffness; then, it is useful to measure how far the actual structural behaviour is from the funicular one by means of the generalized eccentricity. This measure was used in 2018 to define the Relaxed Funicularity (R-Funicularity), a concept according to which a shell is still funicular when the generalized eccentricity belongs to an admissibility domain. Later, a shape optimization procedure aimed at finding R-Funicular shells was proposed and implemented in a MATLAB based tool named R-Fun Optimization, integrated with the Finite Element analysis solver SAP2000. In this work, R-Fun Optimization is extensively discussed and used to optimize the shape of a bi-parabolic shell roof with respect to six objective functions somehow depending on the generalized eccentricity. The results obtained with three different boundary conditions are showed and compared to those obtained in literature with different shape optimization approaches. Also, a graphical representation of the objective functions over the variables domain is given and used to discuss their performances. Finally, a few numerical examples where the geometry is described by means of B-spline are proposed and, in one case, the isogeometric refinement is applied in order to improve the local control of the shape in the optimization process
Gabriele Rossetti, from a portrait by Dante Gabriel Rossetti, 1848
No full text1 carte de visiteCarte de visite of oil painting by D. G. Rossetti (Surtees No. 442) of Gabriele Rossetti. On verso: note in unknown hand "Gabriele Rossetti in 1848.
Gabriele Rossetti, from a portrait by Dante Gabriel Rossetti, 1848
No full text1 carte de visiteCarte de visite of oil painting by D. G. Rossetti (Surtees No. 442) of Gabriele Rossetti. On verso: note in unknown hand "Gabriele Rossetti in 1848.
A consistent use of the Gurson-Tvergaard-Needleman damage model for the R-curve calculation
No full textThe scope of the present work is to point out a consistent simulation procedure for the quasi-static fracture processes, starting from the micro-structural characteristics of the material. To this aim, a local nine-parameters Gurson-Tvergaard-Needleman (GTN) damage law has been used. The damage parameters depend on the micro-structural characteristics and must be calculated, measured or opportunely tuned. This can be done, as proposed by the author, by using an opportunely tuned GTN model for the representative volume element simulations, in order to enrich the original damage model by considering also the defect size distribution. Once determined all the material parameters, an MT fracture test has been simulated by a FE code, to calculate the R-curve in an aeronautical Al-based alloy. The simulation procedure produced results in a very good agreement with the experimental data
R-Funicularity of shells and effective eccentricity: Influence of tensile strength
No full textThe concept of Relaxed Funicularity (R-Funicularity) has been introduced in [2] to deal with the difficulties of designing a shell with a funicular behavior. The R-Funicularity has been defined by using a parameter called generalized eccentricity: a shell is said to be R-Funicular if the generalized eccentricity belongs to an admissibility domain defined in terms of membrane forces N and bending moments M. Here we define an N − M admissibility domain that includes the shell tensile limit force Nt, not previously taken into account. The proposed domain is well described by a new parameter, the effective eccentricity, and is used to control the tensile stresses occurring on shells designed to be R-Funicular and to work under compression
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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