Comet tapes a big sheet of paper to the wall of the Commons. At the top she writes one question: "Do you like it here?"
"Done!" she says. "Now we just ask everyone."
Wren studies the sheet. "What do you notice? If they all say yes, what do we learn about what to add?"
Comet scratches her head. "Not much, I guess."
Nova projects a list of words onto the wall: how often, when, what, how many. "Would you like a hint?" she asks. "Each of these could become something you measure."
Wren picks up a marker and turns to you. "Data analyst, which of these can we count?"
A variable is anything you try to measure. It can be an object, an event, an idea, a feeling, a time period or another category.
The Commons question has several variables hiding inside it.
How often a member visits is one. When they usually visit is another.
What they would like added is a third. How many times they visited last week is a fourth.
| Variable in the Commons question | What kind of thing it measures |
|---|---|
| How often a member visits | An event that repeats |
| When a member usually visits | A time period |
| What a member would like added | An idea |
| How many times a member visited last week | A count of events |
Some answers are a choice from a list, such as morning or evening. In this course we call these category answers.
Other answers are numbers you can count, add or compare, such as 4 visits. We call these number answers.
Knowing which kind you have tells you what you can do with it later.
| Made-up answer from the Commons story | Category or number? |
|---|---|
| evening | |
| 4 visits last week | |
| quiet study room | |
| 12 visits last month | |
| weekend |
| Statement | True or false? |
|---|---|
| A variable is anything you try to measure. | ? |
| A feeling can never be a variable. | ? |
| "Weekend" is a number answer. | ? |
| "Do you like it here?" tells the crew what to add next. | ? |
Nice measuring. Tomorrow in Count Lab you collect real data by watching, not asking.