Add error messages to ypinterim.default to help users detect common errors easily.
Fixing errors when critvalue is supplied in the ypinterim function.
the argument name of spenfun in the ypinterim function is changed to spendfun.
When the alpha spent is less than 1E-4, the boundaries of that look and the corresponding nominal p-values are now obtained using a (conditional) normal distribution.
When the value of the observed statistic is greater than qnorm(1 - 1E-4/2), the nominal p-values are now obtained using a normal distribution.
The default value for repnum is set to 1E4.
The the results from print and summary of the ypinterim class now show the nominal p-values for the boundaries.
Update the references on the help documents and the DESCRIPTION file as they are now available online.
Add new examples to the ypinterim help documents in order to show how to utilize the argument critvalue in the function clearly.
Error fixed in the example data: the virtual_data has also been changed to have only one group vector.