STAT 134 Lecture Notes - Lecture 4: Eket Language, Asteroid Family
ex :hospital N= 393 ,suppose it si 4.6 ,T= 590 ,a
random SRS of h=5o is taken
suppose I=800 ,find 95% CIfor n
800=11.96 .77.95 Itz (E) °TI
I847.2 ,952.8 ]
usually TI is unknown
Sec 7. 3.1 the expectation and variance of sample mean
we assume pop variance T
'is known
7205 -7209 =P 441-443 Pitman
Population of Nelements
Xi ---XN with mean Mand var r2
ex :Xi =annual income of ith household in US
N:# US household
let Xi --.XN be aSRS
×,=Ist number You pick out of {Xi . --Xn }
X2 =2nd -. -
.
We pick without replacement
Xi -uniform {×,
-.-xn 's
know Pr lX=Xi)=÷u
ECX .
)=¥nx÷= tuzxj =npop mean
vaicxi )='T ¥lxi-n)2=r2 pop var
sdcxi )=p
let T= Xi . .-tXn
ECT )=Ekit ---Xn )=EH ,)t ---ECXN )
=nm
