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Sampling Plan: Examples
Advantage of stopping rule:
–Fixed sample:    4.18% improvement is significant
•Harmful:                Power= 0.001;     Average N= 1700
•No effect:              Power= 0.025;     Average N= 1700
•Low effect:            Power= 0.500;     Average N= 1700
•Beneficial:             Power= 0.975;     Average N= 1700
–Grp sequential: 4.24% improvement is significant 
•Harmful:                Power= 0.001;     Average N=   785
•No effect:              Power= 0.025;     Average N=   987
•Low effect:            Power= 0.477;     Average N= 1330
•Beneficial:             Power= 0.966;     Average N= 1104
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