Practice question · Sort into groups
Sort each pair of variables by the direction of correlation you would expect.
Groups: Likely POSITIVE correlation · Likely NEGATIVE correlation
- Altitude up a mountain and air temperature
- Outdoor temperature and ice-cream sales
- Hours studied and exam score
- Car speed and travel time over a fixed distance
- Hours of exercise per week and resting heart rate
Hints
- Positive means both rise together; negative means one rises as the other falls.
- More exercise -> lower resting heart rate, and higher speed -> less travel time are both inverse.
Show the answer
Likely POSITIVE correlation: Outdoor temperature and ice-cream sales, Hours studied and exam score
Likely NEGATIVE correlation: Hours of exercise per week and resting heart rate, Altitude up a mountain and air temperature, Car speed and travel time over a fixed distance
Why
Temperature/sales and study/score rise together (positive); exercise/heart-rate, altitude/temperature, and speed/travel-time move in opposite directions (negative). Reasoning about direction is the skill, not memorizing pairs.
Practise Statistical Tests and Correlation
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