Data displays
Data can be drawn a dozen ways. Which picture answers the question you were asked, and how do you read one someone else drew?
Where you are 12 inside
What this area is about
A list or table of data rarely shows its pattern at a glance; a display does. Each display suits one kind of data and shows some features while hiding others, so this area is about matching the picture to the data and the question, and about reading a picture honestly.
How these fit together
Categorical data. Bar graphs and pictographs show counts per category, and circle graphs show each category’s share of the whole.
One numerical variable. Dot plots and stem and leaf plots keep every value. Histograms group many values into equal bins, and box plots draw the five-number summary.
Two variables. Two-way tables count individuals by two categorical variables, scatter plots plot two numerical ones as points (x, y), and line graphs follow one measurement over time.
Reading and choosing. Reading a graph starts with the title, labels and units. Misleading graphs shows how a picture with correct numbers can still mislead, and choosing a display matches the picture to the question.
A path through it
Bar graphs come first. After them, in any order: dot plots, reading a graph, and two-way tables. Stem and leaf plots follow dot plots; histograms need both bar graphs and dot plots. Reading a graph leads to misleading graphs and choosing a display. Circle graphs, line graphs and scatter plots have no required place here, and box plots need quartiles from center and spread.
Next: shape of a distribution, correlation and chi-square tests.