Purely categorical

No order or rankings can be used

Ex: Zip codes, hair color

Categorical

No measurable distance between data

Ex: Survey Answers

Quantitative

Data can be ordered

Difference between points is meaningful

Ex: Temp

Quantitative

Interval

Meaningful zero point

Ex: Weight, height

Values can be counted

Observations are limited to a set of values that posess gaps

Ex: # of siblings

Data that can take on any value within some interval

Rounding variables = continuous

Ex: batting average, weight, b/p

"Snap shot"

Measures a variable across different units at approx the same point in time

Sum of frequencies in a given class and all preceding classes

Proportion of observations in a given class and all preceding classes

Cumulative frequency/total # of observations

y=a+bx

Average squared deviation from the mean