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Slika - Shrani.si

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A. Juriˇ<strong>si</strong>ć in V. Batagelj: Verjetnostni račun in statistika 240<br />

✬<br />

Obe regre<strong>si</strong>jski funkciji sta linearni.<br />

✫<br />

Regre<strong>si</strong>jska funkcija<br />

Preslikavo x ↦→ E(Y |x) imenujemo regre<strong>si</strong>ja slučajne spremenljivke Y<br />

glede na slučajno spremenljivko X.<br />

Primer: Naj bo (X, Y ) : N(µx, µy, σx, σy, ρ).<br />

Tedaj je, kot vemo pX(x|y) : N(µx + ρ σx<br />

σy (y − µy), σx<br />

Torej je pogojno matematično upanje<br />

in prirejena spremenljivka<br />

E(X|y) = µx + ρ σx<br />

(y − µy)<br />

σy<br />

E(X|Y ) = µx + ρ σx<br />

(Y − µy).<br />

σy<br />

1 − ρ 2 ).<br />

Na podoben način vpeljemo regre<strong>si</strong>jo slučajne spremenljivke X glede na<br />

slučajno spremenljivko Y . Za dvorazseˇzno normalno porazdelitev dobimo<br />

E(Y |X) = µy + ρ σy<br />

(X − µx).<br />

σx<br />

Univerza v Ljubljani ▲<br />

❙ ▲<br />

▲<br />

● ❙ ▲<br />

▲<br />

☛ ✖<br />

▲<br />

✩<br />

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