PSYCH STATS - M2: Frequency, Distributions, and Percentiles

M2: Frequency, Distributions, and Percentiles

frequency

The number of times a score occurs is the score’s

symbolized by f

frequency

distribution

general name for any organized set of data

N

total number of scores in the data

Simple Frequency Distribution

shows the number of times each score occurs in a set of data

f

number of occurrences

N

the total of all the f(s)

BAR GRAPH

used for nominal and ordinal data

HISTOGRAM

used for a small range of different interval or ratio scores

POLYGON

used for a large number of different scores

normal curve or a normal distribution

The most important frequency distribution

tails

The far left and right portions containing the low-frequency extreme scores are called the ______ of the distribution

normal curve or a normal distribution

It is symmetrical

skewed distribution

not symmetrical as it has only one pronounced tail

negatively skewed distribution

contains extreme low scores that have a low frequency, but does not contain low frequency extreme high scores

positively skewed distribution

contains extreme high scores that have a low frequency, but does not contain low frequency extreme low scores

bimodal distribution

symmetrical distribution containing two distinct humps

rectangular distribution

symmetrical distribution shaped like a rectangle

Relative frequency

proportion of time the score occurs

rel. f

symbol for relative frequency

ref. f = f/N

formula for a score’s relative frequency is?

1.0

Usually when you add the rel. f column in the FDT the total is?

Cumulative frequency

The frequency of all scores at or below a particular score.

Cumulative Frequency Distribution

A table that shows each score's frequency, relative frequency, and cumulative frequency

Percentile

The percent of all scores in the data that are at or below a specific score.

Grouped Distributions

Distributions where scores are combined into small groups and reported as total frequency, relative frequency, or cumulative frequency for each group

Range

The difference between the highest and lowest scores in a set of data

Number of Classes (CI)

The number of groups or classes in a grouped distribution

Class Size

The number of scores in each group or class in a grouped distribution

(cf/N)(100)

Formula for percentile

HS - LS

Formula for Range

square root of N

The formula for number of classes (cl)

R / k

Formula for class size (score)