Error probabilities, inferential

The need to control the experiment-wise error rate may not apply to exploratory analyses. Statisticians often perform formal statistical tests for exploratory purposes. So, no formal hypotheses are stated and no inferences are made based on them. Even though the act of performing formally an exploratory test involves the same steps as inferential testing, it is conceptually different because of the absence of a null hypothesis. The p-value obtained in such a test should be viewed as a measure of the level of inconsistency of the data with the underlying assumptions of the test rather than error probabilities involved in making causal inferences. 

Essentially, there are two separate issues involved in performing an interim analysis a statistical issue, and an administrative or trial management issue. The statistical issue is very similar to the multiplicity issue discussed in the previous paragraph, and it applies to the reasons (1), (2) and (3) above. If we perform an interim inferential test, the overall error probability is inflated. Therefore, if one contem-... 

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