Graphical Displays of Data

bar graph

a graphical display of data where the length of each bar corresponds to the number or percentage of observations in a category or group

• used often with qualitative data

• bars do not touch

frequency distribution

a table that lists data values and their corresponding frequencies (ex: counts)

• data values can be listed individually or grouped into “classes”

relative frequency distribution

represents the proportion of values falling in a given class interval

• same as proportion

• frequencies relative to the other sources in the data

histogram

a graphical representation of a frequency or relative frequency distribution

• y axis represents frequencies or relative frequencies

• x axis represents class intervals

• bars touch

stem-and-leaf plot

represents data by separating each value into 2 parts: the stem and the leaf

• shows the same distributional representation of data as the histogram but also allows the researcher to see individual score values

stem

all but the rightmost digit

leaf

the rightmost digit