Conventions used

There are a number of text conventions used throughout this book.

Code in text: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: “We use the lm function for our outcome model as before but will adjust how we calculate the standard errors using the sandwich package.”

A block of code is set as follows:

library(MASS)
set.seed(123)
ad_data <- data.frame(ad_spend = runif(100, 100, 1000),
                      sign_ups = rpois(100, lambda=20))
# Poisson regression model
model <- glm(sign_ups ~ ad_spend, data=ad_data, family="poisson")
summary(model)

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

x <- c(1, 2, 3)
factor_x <- structure(x, class = "factor",
                      .Label = c("low", "medium", "high"))

Bold: Indicates a new term, an important word, or words that you see on screen. For instance, words in menus or dialog boxes appear in bold. Here is an example: “Found at the top left (accessible via File | New File | R Script), this is where you write and save longer code blocks or scripts for complex analyses.”

Tips or important notes

Appear like this.