- StudyBlue
- Oklahoma
- University of Oklahoma
- Statistics
- Statistics 2113
- Fife
- Stats Ch. 3

Alison F.

Frequency

- number of time a score appears
- symbolized by "f"

Distribution

general name researches use for any organized set of data

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N

total number of scores, not the number of different scores

Simple Frequency Distribution

- shows the number of times each score occurs in a set of data
- found by counting how many times the score appears
- if three participants scored 6, then frequency of 6 is 3

Bar Graph

- use when you have a nominal or ordinal data set
- adjacent bars do not touch
- thus, the x variable is discrete

Histogram

- use when plotting a frequency distribution containing a small number of different ratio or interval scores
- adjacent bars touch because the data is continuous

Polygon

- use when plotting a frequency distribution containing a large set of different ratio or interval scores
- measurements are continuous

Normal Curve

- aka normal distribution
- can't label y axis with specific frequencies
- higher the curve is above the score, the higher the score's frequency
- never touches x-axis
- score with the highest frequency is in the middle
- curve is symmetrical
- extreme scores are tails

Negatively Skewed Distribution

- has extreme low scores that have low frequency
- does not have low frequency, extreme high scores
- bump is on the right

Positively Skewed Distribution

- contains extreme high scores that have a low frequency
- does not contain low frequency, extreme low scores
- bump is on the left

Bimodal Distribution

- a symmetrical distribution containing two distinct bumps, each reflecting high frequency scores
- ex. on a test most students score a 70 or 90, with fewer 60 or 80s

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Rectangular Distribution

- shaped like a circle. jk. jbf. it is a rectie!
- ex. 2 students get As, 2 get Bs... etc

Formula for Relative Frequency for a Score

rel. f = f/n

Relative Frequency Distribution

- a graph shows this
- to find this with a set of data, 1st make a simple frequency table
- ex.

6 1 .05

5 0 .00

4 2 .10

3 3 .15

2 10 .50

1 4 .20

Cumulative Frequency

- frequency of all scores at or below a particular score
- written as cf

Percentile

- the percent of all scores in the data at or below a certain score
- so, if the score of 80 is at the 75th percentile, this means that 75% of the sample scored at or below 80

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