7.2.1

Drawing & Interpreting Graphs

Test yourself

Scatter Graphs

You should ignore outlying values that don’t fit with the general pattern. Outliers can move the line away from the rest of the values.

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Line of best fit

  • The two variables are correlated if you can draw a straight line that lies close to most of the points.
  • This line is called a line of best fit.
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Correlation and line of best fit

  • If it passes through almost all your points then there is strong correlation
  • If the points don’t line up so neatly there is only weak correlation
  • If it is not possible to draw a line of best fit then there is no correlation.
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Positive correlation

  • If the line of best fit slopes upwards the correlation is positive.
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Negative correlation

  • If the line of best fit slopes downwards the correlation is negative.
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No correlation

  • If it is not possible to draw a line of best fit then there is no correlation.

Scatter Graphs - Making Predictions

The line of best fit can be used to make predictions.

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Interpolation

  • Making predictions based within the range of the original data is called interpolation.
  • It is more reliable than extrapolation because we know the pattern of data in this range.
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Extrapolation

  • You can make predictions outside the range of data by extending the line of best fit.
  • This is called extrapolation.
  • Extrapolation is less reliable than interpolation because we cannot be sure the same pattern occurs in data outside our range.

Jump to other topics

1Structure - Models of the Particulate of Matter

2Structure - Models of Bonding & Structure

3Structure - Classification of Matter

3.1The Periodic Table: Classification of Elements

3.2Periodic Trends

3.3Group 1 Alkali Metals

3.4Halogens

3.5Noble gases, group 18

3.6Functional Groups: Classification of Organic

3.7Functional Group Chemistry

3.8Alkanes

3.9Alcohols

3.10Halogenoalkanes

4Reactivity - What Drives Chemical Reaction?

5Reactivity - How Much, How Fast & How Far?

6Reactivity - The Mechanisms of Chemical Change

7Measurement, Data Processing & Analysis

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