Erros em gráficos na notícias
Posted by Armando Brito Mendes | Filed under estatística, visualização
Três exemplos de erros em gráficos nos canais de notícias
Fox News bar chart gets it wrong
Because Fox News. See also this, this, and this. [Thanks, Meron]
Tags: análise de dados, belo, data mining, Estat Descritiva
Exponential water tank
Posted by Armando Brito Mendes | Filed under estatística, materiais ensino, visualização
Uma excelente forma de perceber a distribuição exponencial
Hibai Unzueta, based on a paper by Albert Bartlett, demonstrates exponential growth with a simple animation. It depicts a man standing in a tank with finite capacity and water rising slowly, but at an exponential rate.
Our brains are wired to predict future behaviour based on past behaviour (see here). But what happens when something growths exponentially? For a long time, the numbers are so little in relation to the scale that we hardly see the changes. But even at moderate growth rates exponential functions reach a point where the numbers grow too fast. Once we confirm that our predictions about the future have failed, very little time to react may be left.
All looks safe at first, because the water rises so slowly, but it seems to rise all of a sudden. Oh, the suspense. What will happen to cartoon pixel man?
Tags: definição, inferência
Introduction to social network methods
Posted by Armando Brito Mendes | Filed under ARS - SNA, materiais ensino
Um bom livro online sobre SNA
Robert A. Hanneman and Mark Riddle
Introduction to social network methods
Table of contents
About this book
This on-line textbook introduces many of the basics of formal approaches to the analysis of social networks. The text relies heavily on the work of Freeman, Borgatti, and Everett (the authors of the UCINET software package). The materials here, and their organization, were also very strongly influenced by the text of Wasserman and Faust, and by a graduate seminar conducted by Professor Phillip Bonacich at UCLA. Many other users have also made very helpful comments and suggestions based on the first version. Errors and omissions, of course, are the responsibility of the authors.
You are invited to use and redistribute this text freely — but please acknowledge the source.
Hanneman, Robert A. and Mark Riddle. 2005. Introduction to social network methods. Riverside, CA: University of California, Riverside ( published in digital form athttp://faculty.ucr.edu/~hanneman/ )
Table of contents:
Preface
1. Social network data
2. Why formal methods?
3. Using graphs to represent social relations
4. Working with Netdraw to visualize graphs
5. Using matrices to represent social relations
6. Working with network data
7. Connection
8. Embedding
9. Ego networks
10. Centrality and power
11. Cliques and sub-groups
12. Positions and roles: The idea of equivalence
13. Measures of similarity and structural equivalence
14. Automorphic equivalence
15. Regular equivalence
16. Multiplex networks
17. Two-mode networks
18. Some statistical tools
After word
Bibliography
Tags: ARS\SNA applicações, ARS\SNA intro, grafos
SPSS Internet Resources
Posted by Armando Brito Mendes | Filed under estatística, software
Links para variados sites sobre SPSS
The SPSS Inc website
SPSS are now owned by IBM. The following links lead to the appropriate IBM pages now.
http://www-01.ibm.com/software/analytics/spss/ The home page of the SPSS Inc. website
http://www-01.ibm.com/software/uk/analytics/spss/ SPSS Inc. UK page
(If at some future time SPSS Inc change the structure of their website, you may find that only the first of the above links still works.)
The ASSESS-NEWS list
http://www.jiscmail.ac.uk/lists/assess-news.html Information about it, and an archive of past messages.
Other useful links
news:comp.soft-sys.stat.spss The SPSS newsgroup (this carries fairly heavy traffic).
Tags: IBM SPSS Statistics, software estatístico
SPSS Macros on the Internet
Posted by Armando Brito Mendes | Filed under estatística, materiais para profissionais, software
Alguns sites com macros para SPSS
What sources of SPSS macros are available on the Internet?
Here are a few that I know about; I hope other people will tell us about ones that should be listed but aren’t.
An obvious starting point is SPSS Inc’s own Macro Library at http://www.spss.com/tech/stat/macros/ (it doesn’t contain very many, though, and they are statistical rather than utilities). If you are planning to adapt or write macros, it’s also worth seeing what’s in SPSS Inc’s AnswerNet Solutions. Go to http://www.spss.com/tech/answer/, specify Product; SPSS Base and Free Text: macro, then click on the page’s Search button.Raynald Levesque’s site http://pages.infinit.net/rlevesqu/ includes many pages on macros (including examples and some tutorial materials). But you should also look at the examples in his pages on syntax, as some of these are based on macros.
Newsgroups are also a useful source of macros. Searches of their archives can be very rewarding if you can get your search terms right (see our Other Internet Resources page).
Confidence intervals for proportions, differences between proportions and related quantities. See Dr Robert G. Newcombe’s home page at http://www.uwcm.ac.uk/uwcm/ms/Robert.html. Note that these are SPSS programs rather than macros, despite being described as macros by the author.
Polytomous logistic regression (of particular interest to users of SPSS 8.0 and earlier). For macros by John Hendrickx and Prof. Dr. Steffen Kühnel see http://www.sls.wau.nl/bk/bedrijfskunde/jhendrickx/spss/mlogist/
Regression: evaluating collinearity in models with interactions or non-linear terms. For a macro by Ben Pelzer, Manfred te Grotenhuis, Jan Lammers, John Hendrickx, see http://www.sls.wau.nl/bk/bedrijfskunde/jhendrickx/spss/perturb/perturb.html
Tags: Estat Descritiva, IBM SPSS Statistics, inferência, software estatístico
What’s your kind of beer?
Posted by Armando Brito Mendes | Filed under estatística, visualização
Um bom exemplo de um site cheio de visualizações tipo dashboard
What’s your kind of beer?
Choose your preferred beer strength to begin exploring similar beers.
Explore Similar Beers by:
- Overall
- Aroma
- Taste
- Appearance
About the Data
Popularity and top beer styles are based on the number of users who rated the beer.
Tags: belo
Read Histograms and Use Them in R
Posted by Armando Brito Mendes | Filed under estatística, materiais para profissionais, visualização
Bom tutorial para construir histogramas no R
How to Read Histograms and Use Them in R
The histogram is one of my favorite chart types, and for analysis purposes, I probably use them the most. Devised by Karl Pearson (the father of mathematical statistics) in the late 1800s, it’s simple geometrically, robust, and allows you to see the distribution of a dataset.
If you don’t understand what’s driving the chart though, it can be confusing, which is probably why you don’t see it often in general publications.
Tags: análise de dados, data mining, Estat Descritiva, R-software, software estatístico
IFORS Simulation
Posted by Armando Brito Mendes | Filed under estatística, Investigação Operacional, materiais ensino
Algoritmos e Problemas de Simulação
The following 6 pages are in this category, out of 6 total.
D
E
M
S
T
Tags: otimização, software de otimização
IFORS Queueing_Theory
Posted by Armando Brito Mendes | Filed under Investigação Operacional, materiais ensino
Algoritmos e Problemas Filas de Espera
The following 14 pages are in this category, out of 14 total.
Tags: otimização, software de otimização
IFORS Network_Flow_Problems
Posted by Armando Brito Mendes | Filed under Investigação Operacional, materiais ensino, planeamento
Algoritmos e Problemas de Redes
The following 10 pages are in this category, out of 10 total.
ACFG |
IMN |
N cont.T |
Tags: grafos, otimização, software de otimização
