  We identify three issues permeating the literature on statistical methodology
for incomplete data written for non-specialist statisticians and other
investigators. The first is a mathematical defect in the notation Yobs, Ymis
used to partition the data into observed and missing components. The second are
issues concerning the notation `P(R|Yobs, Ymis)=P(R|Yobs)' used for
communicating the definition of missing at random (MAR). And the third is the
framing of ignorability by emulating complete-data methods exactly, rather than
treating the question of ignorability on its own merits. These issues have been
present in the literature for a long time, and have simple remedies. The
purpose of this paper is to raise awareness of these issues, and to explain how
they can be remedied.
