Organizing and Graphing Quantitative Data Sections 2.3 – 2.4

Frequency Distribution for Quantitative Data

Lists all the classes (intervals) and the # of values in each class (frequency). Class Boundary – midpoint between upper limit of one class and lower limit of next class. Class width = upper boundary – lower boundary. Class Midpoint = lower limit + upper limit 2

Example:

Constructing Frequency Distribution Tables Number of classes - usually Class width. –To approximate class width: Largest value – smallest value Number of classes

Example: Start with Data

Frequency Distribution of Data

Relative Frequency Distribution

Histograms Classes on x-axis, frequencies/relative frequencies/percentages on y-axis. Truncation

Relative Frequency Histogram

Polygon Graph formed by joining midpoints of bars.

Frequency Distribution Curve As the # of data and classes increase the polygon becomes more of a smooth curve.

Shapes of Histograms Symmetric

Shapes of Histograms Skewed

Shapes of Histograms Uniform