Make replicate runs of the pilot experiment

Sometimes it is impossible to reproduce an experimental result. The magnitude of variation is too large to be due to a random error. When this happens, the cause of the failure is often that some important experimental factor has been overlooked 

The ability to reproduce the pilot experiment is therefore a good check to see if a screening design will be meaningful. There is another benefit of a replicated pilot experiment the observed variations in response give an estimate of the experimental error, which then can be used to evaluate the significance of estimated effects. 

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