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Unformatted text preview: 2 2 / / X Y X Y Z s m s n = + = = = = = = = = = = = = = = = + = + 2 , 1 1 1 2 1 1 2 , 1 1 1 ( ) , 1 ( ) , 1 ( ) , , i i i n I I tot i j tot i i j i n I trt i i trt i j n I I err i j i err i i j i tot trt err tot trt err S S X X DF n S S n X X DF I S S X X DF n I S S S S S S DF DF DF Stat 211 Formula Sheet (#3) COMPARING TWO POPULATION MEANS In order to compare two population means x and y you compare  E()=E()E()= x y Var()=Var()+Var()= = is normal for m and n both large.  Large Samples Test for comparing population means COMPARING TWO POPULATION PROPORTIONS E()=E()E() Var()=Var()Var() = The distribution of is normal for: m,m,n,n>5. They all have to be greater than 5.  When 0 is INSIDE the interval, the difference in proportions IS NOT significantly different. ANOVA You want to test for the equivalence of several means. o H = 1 = 2 . I o H A =at least to s are different  Each of the groups we are comparing are treatments or factors.  I= number of treatments X ij is the jth sample from the ith treatment with j=1,.,n i We assume each sample comes from a Normal population with common variance.  We partition the total variability of the data into treatment( in our control good) and error (out of our control bad).  Perfect world: your SStrt=SStot, which would mean that you have no random error, so all the variation that exists is what you have created. 2 1 1 ( ) n i i i Q Y X = =  If H is true then F should be close to 1. If H is false then F should be much larger than...
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This note was uploaded on 10/04/2010 for the course STAT STAT 211 taught by Professor Idontremember during the Spring '10 term at Texas A&M.
 Spring '10
 idontremember

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