Exploratory Analysis and an Honest Chart
Before modelling anything, look: distributions, outliers, relationships between pairs. Then the chart that reports it has to make the truth easy to read, which rules out a truncated axis, a misleading area, and a colour scale nobody can order.
What a learner can do afterwards
- Choose the chart that suits a distribution, a comparison and a relationship
- Redraw a chart with a truncated axis and say what changed in the reader's impression
- Say what an outlier in an exploratory plot should prompt before it is removed
1 · Read
Before modelling anything, you look: shapes of distributions, strange points, and how pairs move together. A scatterplot comes before any correlation number, because numbers alone hide shape.
You plot hours of practice against quiz score, one dot per student. The cloud slopes upward with one far dot. You check that student first instead of deleting the dot. If the check proves an error, like a broken sensor, you may remove it and write down why.
Match the chart to the job: a histogram or box plot for a distribution, a bar chart for a comparison, a scatter or line for a relationship over time. A pie shows one set as fractions of a whole. Correlation needs two numbers per item, like height and weight.
A truncated axis stretches small gaps into big drama, so start bars at zero. When you redraw it honestly, say what the first version made the reader believe.
Plot first, match the chart to the question, start bars at zero, and question outliers before you touch them.
2 · Watch
Take it off screen
Where it sits
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.