CHAPTER 2, 3, DEFINITIONS

Frequency Distribution: an organized tabulation of the number of individuals located in each category

on the scale of measurement

- Shows if scores are generally high or low, concentrated in one area or spread out, allows you to

see the location of any individual score relative to all others

- Can be either a graph or at able

- In either case, same 2 elements presented:

a) Set of categories that make up the original measurement scale

b) A record of the frequency, or number of individuals in each category

With ordinal, interval, or ratio scale – #’s are listed in order, with a nominal scale it doesn’t matter

Proportion: measures the fraction of the total group that is associated with each score

- Are often called relative frequencies because they describe the F in terms of N

Grouped Frequency distribution: table presents groups of scores rather than individual scores the

groups or intervals are called class intervals

FREQUENCY DISTRIBUTION GRAPHS

Basically a picture of the information contained in a frequency distribution table

Graphs for numerical scores measured on an interval or ratio scale

a) Histograms

Width of the bar extends to the real limits

b) Polygon

A dot above each score

For a grouped distribution, dot is above the midpoint between interval

Graphs for nominal or ordinal data 9usually non-numerical values)

a) Bar graph

Essentially same as histogram, with spaces between bars

2 SPECIAL FEATURES OF GRAPSH FOR POPULATION DISTRIBUTIONS:

- Relative Frequency: although cannot find the absolute frequency for each score in a population,

can often obtain relative frequencies

- Smooth Curves: when population consists of numerical values from an interval or ratio scale