Factor 6 — Keyword difficulty as triage only, not a measurement

Claim: Keyword Difficulty (KD), aka SEO difficulty, is a 0-100 proprietary score estimating how hard it is to rank on page one. Each tool uses a different formula:

• Ahrefs weights referring domains heavily.
• Semrush uses a multi-factor formula including authority + SERP features.
• Moz leans on Page/Domain Authority of top 10.

Independent practitioner tests show LARGE divergences — same keyword can score, e.g., KD 23 in one tool, 58 in another, "medium" in a third. Frequent 0/100 edge values misrepresent real difficulty.

Core limits:

• Low predictive validity. Practitioner (Omniscient Digital) notes KD has "low to no predictive validity" and only one study correlates KD with performance — with weak statistics.
• Ignores your domain. A "low KD" keyword is still unwinnable if the top results are Wikipedia or a government site — link counts don't capture brand/entity authority.
• Ignores intent and commercial value. A KD-5 keyword with no buyer intent is worth less than a KD-40 keyword with qualified buyers.

Confidence: Industry-consensus / Single-source.

Why this matters for Candid: KD is a legitimate triage / prioritization signal — useful to separate "obviously brutal" from "possibly winnable" — but must NOT be presented as a precise difficulty measurement, and the actual SERP must be inspected. If the widget ingests any vendor KD score, show it as a rough band and pair with a "look at who actually ranks" prompt.