Suppose that the researcher wants to find how increasing the amount
of a certain chemical in the soil increases the amount
that chemical found in the plants.
independent experiments are conducted with
different amounts of the chemical,
and data are produced,
consisting of the amounts
of the chemical in the plants
paired with the respective amounts
of the chemical in soil.
|Amount in soil
||Amount in plant
We call the variable for 's
independent (or explanatory) variable,
and the variable for 's
dependent (or response) variable.
When the relationship between the independent variable
and the dependent variable is approximated by
it is called a simple linear regression model
is introduced as ``random error'' due to difference between
plants, soils, and other possible factors in the experiment.
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