10 I

10.1 IDE

Integrated Development Environment: a program that serves as a text editor, file manager, and provides functions to help you read and write code. RStudio is an IDE for R.

10.2 %in%

The match operator, a binary operator that returns a logical vector indicating if there is a match or not for its left operand.

10.3 independent variable

A variable whose value is assumed to influence the value of a dependent variable.

This term is often used in an experimental context. In a regression context, this is equivalent in meaning to predictor variable.

10.4 index

The number that represents an element's location in a vector.

For example, the index of the letter E in the vector LETTERS is 5.

This can also refer to the main page of a website. For example, the address for the main page of the glossary is technically https://psyteachr.github.io/glossary/index.html (but https://psyteachr.github.io/glossary/ invisibly directs you to the index page).

10.5 inferential

Statistics that allow you to make predictions about or comparisons between data (e.g., t-value, F-value, rho)

Contrast with descriptive statistics.

10.6 inner-join

A mutating join that returns all the rows that have a match in the other table.

Inner Join

Figure 10.1: Inner Join

X <- tibble(
  id = 1:5,
  x = LETTERS[1:5]
)

Y <- tibble(
  id = 2:6,
  y = LETTERS[22:26]
)
Table X Table Y
id x
1 A
2 B
3 C
4 D
5 E
id y
2 V
3 W
4 X
5 Y
6 Z
# a columns come first
data <- inner_join(a, b, by = "id")
id x.x y x.y

Order is not important for inner joins, but does change the order of columns in the resulting table.

# b columns come first
data <- inner_join(b, a, by = "id")
x.x id x.y y

See joins for other types of joins and further resources.

10.7 integer

A data type representing whole numbers.

In R, you specify that a number is an integer by adding an L at the end, like 1L, -36L, or 100L.

10.8 intercept

Also referred to as y-intercept, this is a constant corresponding to the value of the \(y\) variable (in a regression context, the response variable) when all predictor variables are set to zero.

10.9 iteration

Repeating a process or function