Expectation
It can be shown that
where and are the expected value and variance-covariance matrix of, respectively, and tr denotes the trace of a matrix. This result only depends on the existence of and ; in particular, normality of is not required.
Read more about this topic: Quadratic Form (statistics)
Famous quotes containing the word expectation:
“No expectation fails there,
No pleasing habit ends,
No man grows old, no girl grows cold,
But friends walk by friends.”
—William Butler Yeats (1865–1939)
“The joy that comes past hope and beyond expectation is like no other pleasure in extent.”
—Sophocles (497–406/5 B.C.)
“The expectation that every neurotic phenomenon can be cured may, I suspect, be derived from the layman’s belief that the neuroses are something quite unnecessary which have no right whatever to exist. Whereas in fact they are severe, constitutionally fixed illnesses, which rarely restrict themselves to only a few attacks but persist as a rule over long periods throughout life.”
—Sigmund Freud (1856–1939)