You can find this post in Blogdown format by clicking hereWhen it comes to analyzing survey data, you have to take into account the stochastic structure of the sample that was selected to obtain the data. Plots and graphics should not be an exception. ...

I am writing a Rmarkdown document with plenty of tables, and I want them in a decent format, e.g. kable. However I don't want to format them one by one. For example, I have created the following data frame in dplyrdata2 %__% group_by(uf) %__% sum...

As I currently am the NPM for PISA in Colombia, I must assist to several meetings dealing with the proper implementation of this assessment in my country. Few of them are devoted to the analysis of this kind of data (coming from IRT models). As usual, ...

The R package samplesize4surveys contains functions that allow to calculate sample sizes for estimating proportions, means, difference of proportions and even difference of two means. It also permits the calculation of sample error and power level for ...

In an article called A Paradox in the Interpretation of Group Comparisons published in Psychological Bulletin, Lord (1967) made famous the following controversial story:A university is interested in investigating the effects of the nutritional diet its...

It was a Saturday morning; I was lecturing my students of my Item Response Theory class when I decided to run some R scripts to introduce my students with the JAGS syntax and the estimation of parameters in a Bayesian logistic regression setup.As it wa...

Linear models fail to recognize the effect of clustering due to intraclass correlation accurately. However, under some scenarios force you to take into account that units are clustered into subgroups that at the same time are nested within larger group...

For sure, this is the more exciting forecast I have ever done. On one hand, I am Colombian guy, and I really want to live in a peaceful country, and I do want a better place for raising my children. On the other hand, I am very serious when it ...

In a previous entry, we talked about the meaning and importance of isolating confounding variables. This entry is dedicated to the residuals and its relation to the variable of interest when controlling for some confounding factors.Let's think about ed...

Just assume that you have planned a survey along with the necessary sample size to obtain representativity. Let’s suppose the sample size is 100. However, as nonresponse is always present, unfortunately your effective sample size is 99. Consider the...

The main goal of standardised tests is to produce scores that can be compared not only within subgroups of students (and subpopulations of interest) but between applications (in different times). In summary, researchers and methodologists must assure t...

In the assessment of education it is very common to use Item Response Theory in order to produce measures of ability for the students that applied an standardised test. Moreover, if you want to gain comparability between applications you should know th...