# R

• #### An Introduction to Impulse Response Analysis of VAR Models

Impulse response analysis is an important step in econometric analyes, which employ vector autoregressive models. Their main purpose is to describe the evolution of a model’s variables in reaction to a shock in one or more variables. This feature allows to trace the transmission of a single shock within an otherwise noisy system of equations and, thus, makes them very useful tools in the assessment of economic policies. This post provides an introduction to the concept and interpretation of impulse response functions as they are commonly used in the VAR literature and provides code for their calculation in R.
• #### Introduction to dplyr

The cleaning and transformation of data belong to the most time consuming parts of any economic analysis. Many graphical or statistical functions in R require specifically formated data to work properly. Although the standard functions of R can be used to prepare your data for further analysis, some people find them a bit labourious for daily applications. Therefore, alternatives have been developed, which make data transformation in R easier and also faster.
• #### An Introduction to Vector Error Correction Models (VECMs)

One of the prerequisits for the estimation of a vector autoregressive (VAR) model is that the analysed time series are stationary. However, economic theory suggests that there exist equilibrium relations between economic variables in their levels, which can render these variables stationary without taking differences. This is called cointegration. Since knowing the size of such relationships can improve the results of an analysis, it would be desireable to have an econometric model, which is able to capture them.
• #### An Introduction to Bayesian VAR (BVAR) Models

Bayesian methods have significantly gained in popularity during the last decades as computers have become more powerful and new software has been developed. Their flexibility and other advantageous features have made these methods also more popular in econometrics. This post gives a brief introduction to Bayesian VAR (BVAR) models and provides the code to set up and estimate a basic model with the bvartools package. BVAR models Bayesian VAR (BVAR) models have the same mathematical form as any other VAR model, i.
• #### Bayesian Error Correction Models with Priors on the Cointegration Space

Introduction This post provides the code to set up and estimate a basic Bayesian vector error correction (BVEC) model with the bvartools package. The presented Gibbs sampler is based on the approach of Koop et al. (2010), who propose a prior on the cointegration space. Data To illustrate the estimation process, the dataset E6 from Lütkepohl (2007) is used, which contains data on German long-term interest rates and inflation from 1972Q2 to 1998Q4.
• #### Stochastic Search Variable Selection

Introduction A general drawback of vector autoregressive (VAR) models is that the number of estimated coefficients increases disproportionately with the number of lags. Therefore, fewer information per parameter is available for the estimation as the number of lags increases. In the Bayesian VAR literature one approach to mitigate this so-called curse of dimensionality is stochastic search variable selection (SSVS) as proposed by George et al. (2008). The basic idea of SSVS is to assign commonly used prior variances to parameters, which should be included in a model, and prior variances close to zero to irrelevant parameters.
• #### Reproduction: Timmer, M. P., Dietzenbacher, E., Los, B., Stehrer, R., & De Vries, G. J. (2015). An illustrated user guide to the world input–output database: the case of global automotive production.

As international trade has become increasingly fragmented over the past decades the analysis of global value chains (GVC) has gained popularity in economic research. This post reproduces Timmer et al. (2015), who introduce the world input-output database (WIOD) and present basic concepts of GVC analysis. Data Timmer et al. (2015) use the 2013 vintage of the world input-output database (WIOD). The following code downloads the data from the project’s website, unzips it and loads the resulting STATA file into R using the readstata13 package.
• #### William Shakespeare's Work in a Word Cloud

Word or tag clouds seem to be quite popular at the moment. Although their analytical power might be limited, they do serve an aesthetic purpose and, for example, could be put on the cover page of a thesis or a presentation using the content of your work or the literature you went through. This post uses text data from the Gutenberg project to give a step-by-step introduction on how to create a wordcould in R.

• #### An Introduction to Vector Autoregression (VAR)

Since the seminal paper of Sims (1980) vector autoregressive models have become a key instrument in macroeconomic research. This post presents the basic concept of VAR analysis and guides through the estimation procedure of a simple model. When I started my undergraduate program in economics I occasionally encountered the abbreviation VAR in some macro papers. I was fascinated by those waves in the boxes titled impulse responses and wondered how difficult it would be to do such reseach on my own.
• #### Data Visualisation in R Using ggplot2

A major challenge in data analysis is to summarise and present data with informative graphs. The ggplot2 package was specifically designed to help with this task. Since it is a very powerful and well documented package1, this introduction will only focus on its basic syntax, so that the user gets a better understanding of how to read the supporting material on the internet. ggplot graphs are built with some kind of blocks, which usually start with the function ggplot.