Anecdotal evidence is evidence from anecdotes: evidence collected in a casual or informal manner and relying heavily on or entirely on personal experience/testimony or the experiences of friends.
ANECDOTAL EVIDENCE IS UNRELIABLE, WHY?
- Your personal experiences and/or your friends experiences are not evidence of how everyone else reacts or thinks.
- Anecdotal evidence lacks verification and is largely based on very limited context.
- Where only one or a few anecdotes are presented, there is a larger chance that they may be unreliable due to cherry-picked or otherwise non-representative samples of typical cases.
EMPIRICAL EVIDENCE IS RELIABLE, WHY?
Empirical evidence is information acquired by observation or experimentation, in the form of recorded data, which may be the subject of analysis (e.g. by scientists). The below examples illustrate the difference between arguing with anecdotal versus empirical evidence.
ARGUING USING ANECDOTAL EVIDENCE:
“My friend got the COVID-19 vaccine and had really bad side effects. Therefore, the COVID-19 vaccine always causes really bad side effects.”
ARGUING USING EMPIRICAL EVIDENCE:
“Based on a study of 1,000 randomly selected people who received the COVID-19 vaccine, 64% experienced mild side effects, 12% experienced severe side effects, and 24% experienced no side effects.”
Bottom line: Advocacy based on anecdotal evidence is a very poor way to argue. Your personal experiences and your friends’ personal experiences are not evidence of anything, except what happened to you or them individually. Said another way, anecdotal evidence is not data. If you’re going to argue a larger point, make sure to back up your argument with data, and not your personal experiences.