Types of Variables and Summary Statistics

Numeric variables describes a …

measurable quantity

Categorical variables sort data into categories based on …

qualitative description

Numeric variables (UK)

Continuous, Discrete

Categorical variables (UK)

Normal categorical, ordered categorical, Binary

A … variable can take any possible value within a given range

Continuous

A … variable can take specific values within a given range (a count of integers)

discrete

A … variable is divided into different categories not ordered in any way

normal categorical

A … variable is divided into different categories in an ordered manner

ordered categorical

A … is a categorical variable with only 2 categories

binary

… is a variable whose values are graded in equal increments

Interval scale

… same as interval scale, however a true 0 exists (true absence of quantity)

Ratio scale

… a variable that is divided into different categories not ordered in any way

Nominal scale

… a variable that is divided into different categories in an ordered manner

Ordinal scale

A frequency table displays the numbers and the … for each category

proportion

Bar charts display the distribution of a categorical variable, showing the … for each other for easy comparison (same widths, equal spaces between bars

counts

Pie charts show the total … as a circle, they slice the circle into pieces whose size is proportional to the fraction of the whole in each category

population/sample

What are the measures of central tendency?

mean, median, mode

Measures of dispersion is the extent of … of values of a given variable with respect to the central value of a distribution

spread

What are measures of dispersion?

variance, standard deviation, interquartile range

The … is the most common value of this variable

mode

The … is the middle point of a distribution (the value such that half of the observations are smaller and half of the observations are larger)

median

The … is all the values added together and then divided by the number of variables

mean

… is the expectation of a variable to vary/spread around the central location

Dispersion

The … is the largest value (max) - smallest value (min) (Not very informative, highly impacted to extreme values)

range

In a … values are clustered around the mean

normal distribution

The … is used to quantify the typical (‘standard’) spread or variation (or dispersion) around the mean

standard deviation

s is the … of variance which is another measure of dispersion

square root

Histogram is a summary graph for a single numeric variable, the range of values that a variable can take is divided into … of equal size, shows the number of individual data points that fall in each interval

intervals