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

what are bar graphs often used with

qualitative data

do the bars on a bar graph touch and why

no because if they were to touch it indicates some sort of continuum

frequency distribution

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

• data values can be listed individually or grouped into calsses

example for a bar graph

peoples political party affiliation

example for a frequency distribution

evaluating the weights of dogs

relative frequency distribution

represents the portion of values falling in a given class interval; proportion

how to calculate relative frequency

number in a given class/ total number of values

histogram

a graphical representation of a frequency or relative frequency distribution

in a histogram what does the y axis represent

frequencies or relative frequencies

in a histogram what does the x axis represent

class intervals

do the bars in a histogram touch

yes because working with variables that are quantitative

stem and leaf plot

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

what is the stem in a stem and leaf plot

all but the rightmost digit

what is the leaf in a steam and leaf plot

the rightmost digit