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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