جدول مقایسه‌ای از چند منبع

Build a markdown comparison table from the sources below.

Columns: Source | Year | Method | Sample size | Key finding | Limitation

Rules:
- One row per source.
- Pull values verbatim where possible. Don't paraphrase a number.
- If a column is not stated in the source, write "—" (do not guess).
- Below the table, add a 3-line synthesis of where the sources
  agree and where they diverge.

Sources:
"""
[paste source list with abstracts or key passages]
"""