An version of the standard scale for syndrome differentiation of Yin Deficiency Syndrome is not available yet for Chinese medicine.

The aim of this study is to develop and validate the standard scale for syndrome differentiation of Yin Deficiency Syndrome. The study is divided into two steps. The first step is to develop the standard scale for syndrome differentiation of Yin Deficiency Syndrome through expert consultation (Delphi method). The second step is to apply the scale in the participants and find out the diagnostic cut-off value of the scale by comparing it with the gold standard.

Inclusion Criteria:

• Subject will be recruited from the current outpatients' clinic activity of the affiliated hospitals of Beijing University of Chinese Medicine and Nanjing University of Chinese Medicine. Subjects must be able to read and write in Chinese. After obtained informed consent we will ask them to participate to this study.
• All the subjects need to fill in the scale of Yin Deficiency syndrome and be diagnosed by a specialist in traditional Chinese medicine (TCM) to determine whether they have Yin deficiency syndrome. The judgment of TCM experts is the gold standard.

Exclusion Criteria:

• Participates who not meet eligibility criteria

All the subjects were enrolled continuously in the TCM outpatient department. If the informed consent of the researcher is obtained, the scale measurement of the study subjects can be carried out.

After the completion of this study and the publication of relevant research papers, all the research object data in this study will be made public to anyone, but only after de-identification.