Hello everyone. I have a general question that I would appreciate any input on:

Suppose we design a typical group sequential design and to stop (for efficacy or futility) at the first interim analysis the result has to be significant at a nominal p-value of 0.002. Now further suppose that we observe a p-value of 0.025 at this stage. Two questions:

1. Per the GS boundaries we technically cannot stop but how would we interpret this observed p-value. You can imagine a project team asking "yes this result is not significant at the 0.002 level but why can't we say it is significant at the 0.025 level?"

2. If the project team chooses to stop at this stage due to reasons other that statistical (e.g. operationally not feasibility to continue the project) can we use the p-value of 0.025?

So my overall question is how do we interpret these observed interim p-values when they are between stopping bounds

Thank you!

George