R skills

This quiz is designed to help to test basic R skills that we rely on during the course "Introduction to Biostatistics and Machine Learning" such as:

• using R as calculator
• being able to work with vectors and matrices, incl. subsetting and matrices multiplication 
• reading in data from .csv files, e.g. with read_csv()
• printing top few rows or last few rows, e.g. with head() and tail()
• using in-built summary functions such as sum(), min() or max()
• being able to use documentation pages for R functions, e.g. with help() or ?()
• using if else statements, writing simple loops and functions.
• making simple plots (scatter plots, histograms), both with plot() and ggplot()
• using tidyverse() for data transformations, e.g. filtering rows, selecting columns, creating new columns etc. 
• being able to install CRAN packages e.g. with install.packages()
• being familiar with R Markdown format

In case you do not have much R experience or you are unsure about your level, we encourage you to take the quiz. Basically, to comfortably follow the course, you should be able to get all the questions right without much effort, i.e. without needing to google for answers or possible solutions. 

The quiz is anonymous and not linked to the course application in any way. We trust that you apply to the course only if you are meeting the course criteria, including R skills, and do not claim a spot otherwise. 

Instructions

• Use R to perform all the calculations, even if some can be done by hand or using a calculator on your mobile. 
• Each question is worth one point and is meant to test a different R skills, e.g. reading in .csv files or vector operations. 
• You will be able to see the results immediately after finishing and submitting the quiz. Note your score and time.
• Getting all the questions right under 30 minutes means you will be able to follow the course without having to worry about R syntax. We welcome your course application! 
• Note the questions you may struggle with and practise these topics (indicated by the "Testing: ..." label at the top of the question). There are many online tools and books available for learning R, e.g. R for Data Science by Hadley Wickham & Garrett Grolemund 
• After some additional practising  you are welcome to retake the quiz. There are at least three alternatives to each question, drawn at random when you start a new quiz, so you can test your progress. You can retake the quiz as many times you like.