Correlation & regression
Practice Flashcards
What does a scatter diagram show?
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All Flashcards in Topic 4.4
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4.4.19 cards
What does a scatter diagram show?
Paired (x, y) data plotted as points, revealing any relationship between the variables.
How do you describe correlation?
By its direction (positive/negative/none) and its strength (strong/weak).
What does positive correlation mean?
As one variable increases, the other tends to increase too.
What range does Pearson's r take?
From −1 to 1 inclusive.
What does the sign of r tell you?
The direction of the correlation (positive or negative).
What does the size of |r| tell you?
The strength — near 1 is strong, near 0 is weak.
What does r = ±1 mean?
The points lie exactly on a straight line (perfect linear correlation).
Does a strong r prove causation?
No — correlation does not imply causation; a third factor may explain it.
What kind of relationship does r measure?
Linear only — a strong curved pattern can still give a small r.
4.4.29 cards
What is the regression line of y on x?
The best-fit line y = ax + b used to predict y from x.
How do you find the regression line on Paper 2?
Enter the two lists and run linear regression (LinReg) — it gives a and b.
What does the gradient a represent?
The change in y for each 1-unit increase in x.
What does the intercept b represent?
The predicted value of y when x = 0.
Which point does every regression line pass through?
The mean point (x̄, ȳ).
How can you find a mean if you know the line and the other mean?
Substitute the known mean into y = ax + b (the mean point is on the line).
How do you find both means from the two regression lines?
Solve the line of y on x and the line of x on y simultaneously — they meet at (x̄, ȳ).
Which line predicts y from x?
The regression line of y on x.
Which line predicts x from y?
The regression line of x on y.
Topic 4.4 study notes
Full notes & explanations for Correlation & regression
Math AA SL exam skills
Paper structures, command terms & tips
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