Translation

逸話的な / 体験談に基づく / 科学的根拠が弱い

Meaning

Anecdotal describes evidence based on personal stories or isolated experiences rather than systematic data. It can be useful as a clue, but it is weak as proof. Do not confuse it with antidotal, which relates to an antidote.

Examples

• その治療法を支持する証拠は、まだ体験談に基づくものだけでした。
  The evidence for the treatment was still only anecdotal.
• 彼女は体験談ではなく、対照研究を求めました。
  She asked for controlled studies, not anecdotal reports.