2.1 Frequency Distributions (Part 1)

Class Width

the distance between lower (or upper) limits of consecutive classes. Pro Tip: INCLUSIVE & Always round up to the next whole number! Range divided by # of classes.

Important Characteristics of Frequency Distributions

1. Center (middle of your data) 2. Variability (spread between data) 3. Shape (where is the majority of your data/ what trends are shown by the shape)

Frequency Histogram Properties

1. the horizontal scale is quantitative and measures the data values 2. the vertical scale measures the frequencies of the class 3. consecutive bars must touch Pro Tip: y-axis is always frequency x-axis can be midpoints or class limits

Frequency Histogram

a bar graph that represents the frequency distribution of a data set

Frequency Distribution

a table that shows classes or intervals of data entries with a count of the number of entries in each class

Upper Class Boundary

add 0.5 to the upper class limit

Upper Class Limit

greatest number that can belong to a class

Lower Class Limit

least number that can belong to a class

Frequency

of a class is the number of data entries in the class Pro Tip: How often a number comes up that is inside of a specific interval

Relative Frequency

of a class is the portion, or percentage, of the data that falls in that class Pro Tip: frequency (f) divided by sample size (n)

Midpoint

of a class is the sum of the lower and upper limits of the class divided by two, also called class mark

Why do I need boundaries if I have limits?

separate classes WITHOUT forming gaps on the graph Pro Tip: Boundaries include all numbers (decimals) Limits have gaps between each class and do not include the decimals between those numbers

Lower Class Boundary

subtract 0.5 from the lower class limit

Range

the difference between the maximum (highest) and the minimum (lowest) data entries