Page 29 - Math SL HB Sem 3
P. 29
Predictions using the regression line (interpolations and extrapolations):
A regression line can be used to make predictions about the values ofthe dependent variable (y) for any
values of the independent variable (x). However, such are allowed only if lhere is at least a moderately
strong correlation between the two variables.
) lnterpolation - Predictions made within the range of the given data
) Extrapolation - Predictions made outside the range ofthe given data.
The values predicted by extrapolation can be unreliable and must be viewed
wilh caution
\. Exa mple:
Consider the previous example
Circumferences of heads (x)/cm 44.3 48.7 47 .5 45.0 43.1 44.2 48.0 42.6 47 .0
Heights (y)/cm 153 loJ 170 165 160 162 164 15'l 167
y=1.9403x+73.189
a) Use the equation of the regression line to estimate the height of a student whose head
circumference is 46.6 cm.
b) Explain whether or not the estimate is reliable.
c) What does the value 1.9403 in the equation of regression line suggest to you about the
relationship between the head circumference and the height of a person?
d) lnterpret the contextual meaning of73.189 in the equation and comment.
\. sotution:
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