Take a pair of acs objects and combine by rows.
# S3 method for acs
rbind(e1, e2, ...)two acs-class objects
provided for consistency with cbind S3 method
Returns a single new acs object with all of the data contained in the two arguments.
When passed two acs-class objects, rbind will first check to confirm whether the objects contain compatible data: same endyear and span; same column names. If not, it will issue a warning, but will still proceed.
After this check, the function will return a new acs object that has resulted from combining the two arguments row-wise. The effect is essentially the same as rbind on the underlying estimate and standard.error matrices, with all the additional acs metadata tended to.