- SSM Survey SSM (Social Stratification and Social Mobility) project has collected personal histories, concerned with social status and inequality, with national representative samples in Japan. At 1955 the first survey was conducted by the Japanese Association of Sociology. After that basically similar surveys are repeated at intervals of ten years. The fifth survey, which is represented by ...www.nik.sal.tohoku.ac.jp/~tsigeto/ssm/e.html