Download Presentation

Frequency Distributions “ A Picture is Worth a Thousand Words ”

Loading in 2 Seconds...

Frequency Distributions “ A Picture is Worth a Thousand Words ”

Loading in 2 Seconds...

- By
**ivory** - Follow User

- 88 Views
- Uploaded on

Download Presentation
## PowerPoint Slideshow about 'Frequency Distributions A Picture is Worth a Thousand Words ' - ivory

**An Image/Link below is provided (as is) to download presentation**

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

Graphing Techniques

- Bar graph
- For nominal and ordinal data the adjacent bars should not touch
- Histogram
- For interval and ratio data the adjacent bars should touch
- Frequency polygon
- Connect using straight lines; include next highest and next lowest
- Especially useful with overlapping distributions

Types of Frequency Distributions

- Normal distribution or normal curve
- Highest scores in the middle
- Tails are the extreme scores
- Smooth line
- Overlapping distribution

Variations in Normal Distribution

- Mesokurtic = normal distribution
- Leptokurtic = thin
- Platykurtic = broad or fat
- Skewed distributions
- Negatively skewed: low frequency of low scores and higher frequency of high scores
- Positively skewed: low frequency of high scores and higher frequency of low scores
- Bimodal distribution
- rectangular distribution

Remember: Plot Data

- Distribution
- See the pattern
- N = number of scores/sample size
- f = Frequency with which the different scores occur
- What scores occurred and how often
- Create a table before plotting

Simple Frequency Distribution

- The number of times that score occurs
- Make a table with highest score at top and decreasing for every possible whole number
- N (total number of scores) always equals the sum of the frequency
- f = N

Example of a simple frequency distribution

- 5 7 8 1 5 9 3 4 2 2 3 4 9 7 1 4 5 6 8 9 4 3 5 2 1
- f
- 9 3
- 8 2
- 7 2
- 6 1
- 5 4
- 4 4
- 3 3
- 2 3
- 1 3
- f = 25

Relative Frequency Distribution

- Proportion of the total N
- Divide the frequency of each score by N
- Rel. f = f/N
- Sum of relative frequencies should equal 1.0
- Gives us a frame of reference
- Find relative frequency using the normal curve
- Proportion of the total area under the curve

Example of a simple frequency distribution

- 5 7 8 1 5 9 3 4 2 2 3 4 9 7 1 4 5 6 8 9 4 3 5 2 1
- f rel f
- 9 3 .12
- 8 2 .08
- 7 2 .08
- 6 1 .04
- 5 4 .16
- 4 4 .16
- 3 3 .12
- 2 3 .12
- 1 3 .12
- f = 25 rel f = 1.0

Cumulative Frequency Distributions

- cf = cumulative frequency: number of scores at or below a particular score
- A score’s standing relative to other scores
- Count from lower scores and add the simple frequencies for all scores below that score

Example of a simple frequency distribution

- 5 7 8 1 5 9 3 4 2 2 3 4 9 7 1 4 5 6 8 9 4 3 5 2 1
- f rel f cf
- 9 3 .12 25
- 8 2 .08 22
- 7 2 .08 20
- 6 1 .04 18
- 5 4 .16 17
- 4 4 .16 13
- 3 3 .12 9
- 2 3 .12 6
- 1 3 .12 3
- f = 25 rel f = 1.0

Percentile

- Percent of all scores in the data that are at or below a certain point
- Takes into consideration the sample N
- Convert cumulative frequency into percents

Download Presentation

Connecting to Server..