There are a number of astrostatistics-related societies that you may be interested in joining. If you know of others, please let us know.
American Astronomical Society Working Group on Astroinformatics and Astrostatistics (AAS WGAA)
American Statistical Association Astrostatistics Interest Group (ASA AIG)
Cosmostatistics Initiative (COIN)
International Astroinformatics Association (IAIA)
International Astrostatistics Association (IAA)
International Astronomical Union Commission on Astroinformatics and Astrostatistics (IAU CAA)
International Statistical Institute Special Interest Group in Astrostatistics (ISI SIGA)