Evidence Comparison

Evidence comparison is the practice, common in policy debate, Lincoln-Douglas, parliamentary, and Model UN caucus speeches, of explicitly comparing two or more pieces of conflicting evidence rather than simply asserting one's own card or citation. Instead of leaving the judge or chair to decide which source is more credible, the debater does the analytical work on the floor.

Standard comparison criteria include:

• Recency – newer evidence often reflects current conditions, especially on fast-moving issues like sanctions regimes or conflict casualty counts.
• Source qualification – the author's institutional affiliation, peer review status, and subject-matter expertise.
• Methodology – whether claims rest on primary data, modeling assumptions, anecdotes, or secondary reporting.
• Scope and specificity – whether the evidence speaks directly to the contested claim or only tangentially.
• Bias and funding – whether the source has a stake in the outcome (e.g., an industry-funded study versus an independent audit).
• Empirical vs. predictive – historical data is generally treated as stronger than forecasts.

In competitive policy debate, evidence comparison is often phrased as "prefer our evidence because…" and is a core component of the rebuttal stage, where new evidence is typically barred but comparative analysis of existing cards is encouraged.

For Model UN delegates and junior researchers, the same logic applies when reconciling conflicting figures from, for example, a World Bank report and an IMF World Economic Outlook release, or differing casualty estimates from the UN Office for the Coordination of Humanitarian Affairs and a national government. Strong delegates do not just cite a number; they explain why their source should be trusted over the alternative.

Failure to engage in evidence comparison often results in what judges call "ships passing in the night" — both sides reading credible-sounding evidence past each other with no resolution. Good comparison forces a decision and frequently determines the outcome of close rounds.