Numbers that tell a story

The idea

A statistical statement is a claim or summary about some phenomenon, expressed in terms of numerical values, proportions, probabilities or predictions.

The two friends

Your teacher is meeting two childhood friends this evening. One is 5 feet tall and the other is 6 feet tall.

Which friend is more likely to be a man?

• The 6-foot-tall friend
• The 5-foot-tall friend
• Nobody can say anything

Sort the statements

Each card is a sentence. Is it a statistical statement? If yes, what does it use: a number, a share, a chance or a prediction?

A claim with numbers

The guess about the two friends is a small piece of statistical thinking. Men are more often taller than women. So 6 feet more likely means a man. We may be wrong, because 5-foot men and 6-foot women exist, but they are rare.

A statistical statement is a claim or summary about some phenomenon, expressed in terms of numerical values, proportions, probabilities or predictions.

• It uses | Example
• Number | about 15 minutes to cycle
• Share | 3 out of every 4 students
• Chance | 70% chance of rain
• Prediction | the pen may last 2 more weeks

Notes

A statistical statement is a claim or summary about some phenomenon, expressed in terms of numerical values, proportions, probabilities or predictions.

Check yourself

Which of these is a statistical statement?

A statement says: “The 6-foot-tall friend is probably a man.” You meet them, and the 6-foot-tall friend is a woman. What does this show?

Which kind is this statement: “There is a 30% chance of a thunderstorm tonight”?

Suppose exactly 3 out of every 4 students in a class come by bus. The class has 40 students. How many come by bus?

Answer: 30

40 ÷ 4 = 10 groups of 4 students. Each group has 3 bus students: 10 × 3 = 30.

• Ria is a very kind girl.. That is an opinion. It has no number, share, chance or prediction.
• Ria takes about 20 minutes to walk to school. — correct. Yes! It sums up her walks with a number: about 20 minutes.
• The Taj Mahal is white.. That only describes how something looks. It has no number, share, chance or prediction.
• The statement can be wrong for one person. It still tells what happens more often. — correct. Yes! Statistical statements describe what is more usual. Rare cases exist.
• So it was not a statistical statement at all.. A statistical statement does not have to be right every time. It says what is more often true.
• So the 5-foot-tall friend must be a man.. One surprise does not decide the other friend. Each person is a separate guess.
• A share (proportion). A share says how many out of a group have something. This says how likely a future event is.
• A chance (probability) — correct. Yes! It says how likely something is.
• Not a statistical statement. It has a number, 30%, and says something about tonight. It is statistical.