STAT141 Chapter Notes -Voer, Summary Statistics, Xnu

• School: University of Alberta
• Department: Statistics
• Course: STAT141
• Professor: Oksana Kotovych

Document Summary

Independent selection of individuals doesn"t influence the selection of individuals for other sample. From pop 2 n1 n2 n1 and n2 don"t have to be equal! The sampling distribution of 1- 2: take a sample of size n1 from pop 1. Compute 1. : take a sample of size n2 from pop 2. Compute 2. : compute 1- 2, repeat steps 1-3 many times, construct a histogram of all the values of ( 1- 2). General properties: e( 1- 2) = e( 1) - e( 2)= 1- 2 = ( 1- 2) this is the mean of all the values of ( 1- 2). : var( 1- 2) = var( 1) + var( 2) the equal sign shows independence. = ( 1- 2) = sd of all the values of ( 1- 2). We approximate this with the standard error: se( 1- 2) = In each group, n should be reasonably large or the population distribution should be roughly normal.