EC255 Chapter Notes - Chapter 2: Interval Class, Frequency Distribution
Document Summary
Ungrouped data: not aggregated / not summarized, also called raw data. Grouped data: aggregated data, already organized into frequency distribution, already organized into histogram. Summary of data presented in the form of class intervals and frequencies. Steps: determine the range of raw data. The difference bw the largest and smallest numbers: determine how many classes it will contain. Usually bw 5 and 15 classes: determine width of the class interval. Approximation can be found by dividing range by the number of classes. Freq. distribution must start at a value equal to or lower than the lowest number of the ungrouped data. End at a value equal to or higher than the highest number. Midpoint of each class interval = class midpoint the value halfway across the class interval calculation: average of the two class endpoints becomes the representative value for each class.
