Saturday, March 5, 2011

KNNL - Random Effects Models – chapter 25


 

-          factor levels sample from larger population

-          example

o   several hundred stores

o   seven chosen at random

o   sample of employees chosen at each store

-          example

o   8 employees selected at random from each of the 5 depts in each store

o   interest now in employee evaluation of mgt by dept and store

o   stores – random factor

o   depts. – fixed factor

-          repetition would involve new sample which would probably consist of different subjects

-          Yij = ui + ξij

-          factor level means – random variables

-          difference between two models (fixed and random effects) appears in expected mean squares

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