Equation to describe a regression line
A regression line could be drawn 'by eye' through a scatterplot, but we restrict attention to simple mathematical functions
y = ƒ ( x )
since they are easier and more objective to use.
Linear model
Some relationships must be described by curves, but a straight line is an adequate description of many bivariate data sets.
y = b0 + b1 x
The constant b0 is the intercept of the line and describes the y-value when x is zero. The constant b1 is the line's slope; it describes the change in y when x increases by one.
The predicted response at any x-value is
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= b0 + b1 x |