Data and variables
Someone hands you a pile of answers about a group. What has to happen before those answers can tell you anything?
Where you are 8 inside
What this area is about
Data are facts recorded about a group of individuals, and a variable is one thing recorded about each of them. Before any graph or average, data have to be gathered from a question worth asking, labeled so each value means something, and sorted and counted. This area covers those first steps, from sorting buttons to a table of shares.
How these fit together
Sorting and counting. Sorting objects into categories puts a mixed pile into groups by one rule; counting and ordering categories finds which group has the most and which the fewest.
Asking. A statistical question expects its answers to vary; collecting data with a survey asks it of each person in fair words and records every answer.
Reading a data table. Individuals and variables are the rows and columns of a data table. Categorical and numerical data tells values that name a group from values that count or measure an amount.
Summarizing counts. Frequency tables count each category; relative frequency tables turn each count into a share of its total, such as \displaystyle \frac{28}{80} = 0.35, so groups of different sizes compare fairly.
A path through it
Within each pair, the first comes first: sorting before counting and ordering, the question before the survey, individuals and variables before data types, counts before shares.
Finish here and you are ready to make a bar graph or a histogram, choose a display, find the mean from a frequency table, and spot response bias in a survey.