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Chapter 2: Organizing Data. Section 2: Frequency Distribution and Histograms. Frequency Distribution. Lists the number of occurrences for each category of data. Classes. Categories of data created by using intervals of numbers Usually 5 to 15 classes.
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Chapter 2: Organizing Data Section 2: Frequency Distribution and Histograms
Frequency Distribution • Lists the number of occurrences for each category of data
Classes • Categories of data created by using intervals of numbers • Usually 5 to 15 classes.
The difference between consecutive lower class limits To find the class width… 1. largest data value – smallest data value desired number of classes 2. Increase result to next whole number Class Width
The smallest value within the class. The largest value within the class . Class Limits Upper Class Limit Lower Class Limit
the relative frequency is listed, found by dividing the frequency (f) of each class by the sum of all the frequencies (n). class frequency (f) total of all frequencies (n) Relative Frequency Distribution
Class Mark (Mid-Point) • The number halfway between the lower and upper class limits of a class. To find the class mark… lower class limit + upper class limit 2
Graphic representations of (Grouped) Frequency Distributions • Histogram- A type of bar graph. - Horizontal axis represents classes by labeling the class boundaries - vertical axis represents frequency or relative frequency - no space between bars · - bars must be the same width - width of bar represents a quantitative value, rather than a category
Class Boundary • the halfway point between the upper limit of one class and the lower limit of the next class • used as endpoints of the bars in a histogram
Three Classes Fr equency
Histogram Examples (Cont). frequency Five Classes TenClasses F F F F F F F FFFFFF
Frequency Polygon • type of line graph, horizontal axis labeled with class marks, vertical axis represents frequencies
Relative frequency distribution for Scores on a Scientific Achievement Test
Relative frequency distribution for Scores on a Scientific Achievement Test