# 03. Review of Basic Data Analytic Methods Using R Flashcards

What is a factor

A factor is vector of values that are limited to a fixed set of values (categories). Factors always have levels (the things it allows to be put in - like it had a data validation drop down list). When you first create the factor it will assume the different options are the initial options, after that it will check against this set of levels.

What is a list

A list is a vector of values which can contain different data types

What is an array

An array can only contain the same type of data. Arrays can multi-dimensional. i.e. rows and columns and sheets and workbooks etc

What is a dataframe

A dataframe is a table of vectors or factors; all items of the same length. Individual columns are the same data type, but different columns can be different data types.

What is a record

A single cell

What is a pairs plot

It plots every variable against every other variable. Also known as a Splom or a ScatterPlot

What do T-Tests use

Samples of the population (not the full population)

What are T-Tests use

Samples of the population (not the full population) are tested to compare against a NULL hypothesis (i.e. checking if there is a statistical significance)

What can an AVOVA test be used for

AVOVA are used in hypothesis testing when you have more than two sample populations

What is hypothesis testing

where you are picking between the null and the alternative hypothesis

What is statistical power

Statistical Power is a measure of how well that test compares against the null

What is a parametric distribution

The data follows a normal distribution

How is the standard deviation calculated

The standard deviation is the square root of the deviance

The T-Test

Parametric. Can be one test and two test

A “students t-test” is another name for the two sample t test.

Welch’s test

Parametric. But can cope with different standard deviations (hence automatically two sample)