# Chapter 2: Organizing Data - PowerPoint PPT Presentation

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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

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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)

### 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

frequency

Five Classes

TenClasses

F

F

F

F

F

F

F

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### Frequency Polygon

• type of line graph, horizontal axis labeled with class marks, vertical axis represents frequencies