Depending on the interval argument of
predict_adjust:
A vector of predictions if interval = "none".
A matrix of predictions and bounds with column names
fit, lwr, and upr if
interval is set. For type = "terms" this
is a matrix with a column per term and may have an
attribute "constant".
If se.fit is TRUE, a
list with the following components is returned:
fit: vector or matrix as above
se.fit: standard error of predicted means
residual.scale: residual standard deviations
df: degrees of freedom for residual