Introduction to regression
Introduction to regression
Introduction to regression
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Chapter 3 <strong>Introduction</strong> <strong>to</strong> <strong>regression</strong> 123<br />
Interpretation, interpolation and<br />
extrapolation<br />
Interpreting slope and intercept (m and b)<br />
Once you have a least-squares <strong>regression</strong> line, the slope and intercept can give important<br />
information about the data set.<br />
The slope (m) indicates the rate at which the data are increasing or decreasing.<br />
The y-intercept indicates the approximate value of the data when x = 0.<br />
WORKED Example<br />
5<br />
In the study of the growth of a species of bacterium, it is assumed that the<br />
growth is linear. However, it is very expensive <strong>to</strong> measure the number of<br />
bacteria in a sample. Given the data listed below, find:<br />
a the rate at which bacteria are growing<br />
b the number of bacteria at the start of the experiment.<br />
Day of experiment 1 4 5 9 11<br />
Number of bacteria 500 1000 1100 2100 2500<br />
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