1.2 Working with Categorical Data

simulation

a random reenactment of data collection under one or more assumptions - if real data looks significantly different from simulated data, then said assumptions are questioned

distribution

each of a variable gives the possible values of the variable and the relative frequency of each value

relative frequency table

a table that lists the categories of a categorical variable and gives the relative frequency of each category

side-by-side bar chart

a bar chart that groups the bars of two or more conditional distributions side by side

relative frequency

the ratio of the number of observations in a category to the total number of observations - represented as a fraction or percentage

pie chart

a circle sliced into pieces whose sizes are proportional to the fraction of the whole in each category

categorical data condition

the conditions that data uses to create frequency tables, relative frequency tables, bar charts, pie charts, contingency tables, segmented bar charts, side-by-side bar charts, and mosaic plots must be non-overlapping categorical data

area principle

the area occupied by a part of a graph should correspond to the amount of data it represents

categorical variable

a variable that names categories using words or numbers

bar chart

a graph consisting of bars whose area represents the count of observations for each category of a categorical variable, always with gaps separating the bars

mosaic plot

a special kind of segmented bar chart whose bars’ widths display the marginal distribution of the variable represented by the bars

simpson’s paradox

averages that are taken across different groups, which can appear to contradict the overall averages

marginal distribution

the distribution of values for individual variables in a contingency table

contingency table

a table showing counts and sometimes percentages of individuals falling into named categories on two or more variables, used to possibly reveal variables dependent on one another

conditional distribution

the distribution of a variable restricting the Who in order to consider only a smaller group of individuals

frequency table

a table that lists the categories of a categorical variable and gives the number of observations in each category

segmented bar chart

a bar chart whose bars are stacked on top of one another in a vertical graph or are lined up side by side in a horizontal graph

independence

variables are said to be if the conditional distribution of one variable is the same for all categories of another variable - if variables are to each other, there is no association between them