Stata FAQ: How can I draw a random sample of my data? Stata FAQ How can I draw a random sample of my data? There are many instances when you may want to take a random sample of your dataset. For example, you may have a very large data set, and you are trying to work out the code to clean your data or to analyze it. Why R is Hard to Learn by Bob Muenchen R has a reputation of being hard to learn. Some of that is due to the fact that it is radically different from other analytics software. Some is an unavoidable byproduct of its extreme power and flexibility. FAQ: Using a plugin to connect to a database How do I connect to a database by using a Stata plugin? ODBC vs. plugin The easiest way to import data from a database directly into Stata is to use the odbc command.
DVR TIG Week: Tony Fujs on Dataviz with the Grammar of Graphics: R you Ready? Hello! I’m Tony Fujs, Director of Evaluation at the Latin American Youth Center, a DC based non-profit organization. Today, I want to share my experience using R and ggplot2 for data visualization. Ggplot2 is a great tool from the R toolbox (a package, in R lingo). It relies on the powerful Grammar of Graphics framework, which helps “shorten the distance from mind to paper” (Hadley Wickam). I started using R three years ago, and it has now become my main tool for data analysis and visualization.R is known to have a steep learning curve though, so before getting started, it’s probably a good idea to do a little bit of “cost-benefits” analysis, and check if R is a good fit for you.
Mike Bader’s Blog Monday, June 6th, 2011 6:37p.m. Programming in Stata is relatively straightforward and this is partly because the programming syntax is both powerful and relatively straightforward. There are, however, a few minor annoyances in Stata's language including using the backtick and apostrophe to indicate local macros (i.e. Beginner's guide to R: Introduction R is hot. Whether measured by more than 4,400 add-on packages, the 18,000+ members of LinkedIn's R group or the close to 80 R Meetup groups currently in existence, there can be little doubt that interest in the R statistics language, especially for data analysis, is soaring. Why R? 8.7 ARIMA modelling in R How does auto.arima() work ? The auto.arima() function in R uses a variation of the Hyndman and Khandakar algorithm which combines unit root tests, minimization of the AICc and MLE to obtain an ARIMA model. The algorithm follows these steps. Hyndman-Khandakar algorithm for automatic ARIMA modelling The number of differences $d$ is determined using repeated KPSS tests.The values of $p$ and $q$ are then chosen by minimizing the AICc after differencing the data $d$ times. Rather than considering every possible combination of $p$ and $q$, the algorithm uses a stepwise search to traverse the model space.
Stata Programming Essentials Ever needed to do the same thing to ten different variables and wished that you didn't have to write it out ten times? If so, then this article is for you. If not, someday you will—so you might as well keep reading anyway.
Statistical Learning About This Course This is an introductory-level course in supervised learning, with a focus on regression and classification methods. The syllabus includes: linear and polynomial regression, logistic regression and linear discriminant analysis; cross-validation and the bootstrap, model selection and regularization methods (ridge and lasso); nonlinear models, splines and generalized additive models; tree-based methods, random forests and boosting; support-vector machines. Some unsupervised learning methods are discussed: principal components and clustering (k-means and hierarchical). ARIMA Modelling of Time Series Description Fit an ARIMA model to a univariate time series. Usage arima(x, order = c(0L, 0L, 0L), seasonal = list(order = c(0L, 0L, 0L), period = NA), xreg = NULL, include.mean = TRUE, transform.pars = TRUE, fixed = NULL, init = NULL, method = c("CSS-ML", "ML", "CSS"), n.cond, SSinit = c("Gardner1980", "Rossignol2011"), optim.method = "BFGS", optim.control = list(), kappa = 1e6) Arguments