Some questions are not about bars
Does a dearer product sell less? Who bought both a football and a bottle? Which words do customers use most? A bar chart cannot answer all of these well.
Some data is about links between things, groups that overlap, steps in a process, or words. Each needs its own picture.
By the end of this lesson
Note
I can choose a scatterplot, a diagram or a word cloud when the data is about links, groups, steps or words.
Key words
| Word | What it means |
|---|---|
| Scatterplot | a chart with one dot for each record, on two number axes |
| Correlation | two things that tend to rise or fall together |
| Overlap | items that belong to two groups at once |
| Word cloud | a picture of words, bigger when used more |
| Tree diagram | a diagram that splits a thing into branches |
The cells students fill in are left blank in this preview.
Starter: what you already know
Have a go
Starter: what you already know
4 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Scatterplots show how two numbers relate
A scatterplot puts one dot on the chart for each record. One number goes along the bottom axis, and another goes up the side. If the dots slope upwards or downwards, there may be a correlation.
A bubble chart adds a third number: the size of each dot. A density plot shows where dots crowd together.
Try it: the points of a scatterplot
-- Each row is one dot: price across, units sold up.
SELECT products.product_name AS Product,
products.price AS Price,
COALESCE(SUM(sales.quantity), 0) AS Units
FROM products
LEFT JOIN sales ON sales.product_id = products.product_id
GROUP BY products.product_id
ORDER BY products.price;
-- Is there a clear link between price and units? Talk about it.
A common mistake
Warning
Many people think that when two things move together, one causes the other. Not always. Ice cream sales and sunburn both rise in summer, but ice cream does not cause sunburn. A correlation is a clue to look further, not proof of a cause.
Check
Have a go
Check
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.