Variance decomposition formula, conditional variance formulas or law of iterated variances also known as Eve's law
EVPV(expected value of the process variance) + VHM (variance of the hypothetical means)
X의 변화에 따른 Y의 평균 변동성 + X를 알고도 남는 Y의 불확실성
XY 2차원 분포 생각하면 이해 편하다 - E[], V[] 결과가 상수가 아니라 함수로 나옴 적분위해
decomposes the variance of two random variables on the same probability space into "explained" and "unexplained" components
Eve's law, from the initials EV VE for "expectation of variance" and "variance of expectation".