just like data
but "these data" just sounds wrong
( Gilgamesh gazed in wonder as Frampton came alive, Tue 26 Dec 2006, 22:48, archived)

but you do see "datum" used sometimes
unlike "medium" (when referring to just one newspaper)
( Grrrmachine the indifference engine, Tue 26 Dec 2006, 22:49, archived)