The relevant code has been moved out of the sandbox and is now at statsmodels.stats.multitest
The sandbox function are just alias for the non-sandbox functions. The online documentation is currently a bit outdated.
The direct import
>>> from statsmodels.stats.multitest import fdrcorrection
>>> fdrcorrection
<function fdrcorrection at 0x0000000008554B70>
using it through the api
>>> import statsmodels.api as sm
>>> sm.stats.fdrcorrection
<function fdrcorrection at 0x0000000008554B70>
this is the old location which currently still contains an alias
>>> from statsmodels.sandbox.stats.multicomp import fdrcorrection0
>>> fdrcorrection0
<function fdrcorrection at 0x0000000008554B70>
edited list of functions in statsmodels.stats.multitest
:
>>> import statsmodels.stats.multitest as multi
>>> dir(multi) # output edited
['NullDistribution', 'fdrcorrection', 'fdrcorrection_twostage', 'local_fdr', 'multipletests']