AP Statistics › How to find confidence intervals for the slope of a least-squares regression line
You estimate a regression model with and
, where
is the beta coefficient and
is the standard error. Construct 95% confidence intervals for
.
To construct 95% confidence intervals for , we simply take the coefficient and add/subtract
. This is because
is assumed to follow a symmetrical distribution (the normal), and 95% of the values in the sampling distribution are contained within 1.96 standard errors of
.