Flashcards · Maths · Statistics
Scatter Graphs
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What is a scatter graph?
A graph that plots pairs of values to show whether two variables are related.
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What is positive correlation?
As one variable increases, so does the other.
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What is negative correlation?
As one variable increases, the other decreases.
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What does no correlation look like?
Scattered points with no pattern.
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What is a line of best fit?
A straight line through the middle of the points, showing the trend.
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How should you draw a line of best fit?
With a ruler, with roughly equal numbers of points above and below and ignoring outliers.
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What is an outlier?
A point that is far from the pattern of the others.
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What is interpolation?
Estimating a value inside the range of the data.
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What is extrapolation?
Estimating a value outside the range of the data.
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Why is extrapolation unreliable?
The trend may not continue.
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Does correlation prove one thing causes another?
No.
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What does the gradient of a line of best fit mean?
The change in the vertical variable for each unit increase in the horizontal variable.
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What does the \(y\)-intercept of a line of best fit mean?
The estimated value when the horizontal variable is zero.
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The line \(y = 4x + 8\) estimates the score for 12 hours of revision as?
\(4 \times 12 + 8 = 56\).
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Why is a larger sample better?
The line and correlation are more trustworthy.
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How should you describe correlation in an exam?
Use the variable names, such as "as age increases, value decreases".