Which of the following analysis are incredibly hard to infer ?

Inferential Causal Exploratory Mechanistic

What is the backup class of a data.table?

data.frame data-frame function matrix

Which programming languages are most popular for data science?

SQL, Python, and R F#, Erlang, and LISP C#, Java, and Javascript SPSS, SAS, and Stata

What can you do with the 'by' parameter of a data.table?

Group the output table Select a specific column Add an extra row to your dataset Connect several filter criteria

What function do you use in the caret package to determine the accuracy of your machine learning models?

confusionMatrix() predict() score() accuracy()