Appendix A. Claims and Evidence Grades
This list is the reference for every Kairu short, video, lesson and ad. Each script is tagged with the claim it relies on, and its wording matches the grade: A → "research shows"; B → "one study found" or "professionals report"; C → "a method consultants use" or "our recommendation." Claim IDs follow the chapter number so they stay stable as the book grows.
| ID | Claim | Grade | Move |
|---|---|---|---|
| 1.1 | Effectiveness is judged by the listener, on both results and fit | A–B | — |
| 1.2 | Communication skill is specific to the situation, so practice situation by situation | B | — |
| 1.3 | Speakers overestimate how clear they are | B | — |
| 3.1 | Telling listeners the topic first roughly doubles comprehension and recall | A | Headline |
| 3.2 | The same information at the end has almost no effect | A | Headline |
| 3.3 | Listeners hold about four chunks; keep to three points | A+C | Headline |
| 3.4 | Consultants and the U.S. Army put the main point first | C | Headline |
| 4.1 | The gap between speakers is about 0.2 seconds in every language studied | A | Enter |
| 4.2 | Disagreement naturally comes out slower; prepare your first line | A+C | Enter |
| 4.3 | "Don't speak without a complete answer" is a common unwritten workplace rule | A | Enter |
| 5.1 | When a decision matters to listeners, the quality of your reasons drives their view | A | Reason |
| 5.2 | Adding weak reasons to a strong one can reduce persuasion | B | Reason |
| 5.3 | Raising the other side and answering it is more persuasive than ignoring it | A | Reason |
| 5.4 | Raising the other side without answering it is the least persuasive option | A | Reason |
| 6.1 | Hesitations and stacked hedges make you sound less competent | A | Own |
| 6.2 | One "I think" in front of a real opinion is fine | B | Own |
| 6.3 | Separate what you know from what you don't | C | Own |
| 7.1 | Stating your conclusion explicitly and specifically is more persuasive than leaving it implied | Asmall effect | Next |
| 7.2 | Plans with who, what and when make follow-through more likely | Asmaller than early estimates | Next |
| 7.3 | Teams that end discussions with next actions perform better | B | Next |
| 8.1 | Global professionals rank clarity and brevity above native-like English | B | Pace / Clarify |
| 8.2 | Asking for clarification is a core skill, not a weakness | B | Clarify |
| 8.3 | For many people, confidence is a bigger barrier than English ability | B | — |
| 9.1 | East Asians' leadership gap in the U.S. is explained by assertiveness norms, not English or motivation | A | Enter, Own |
| 9.2 | South Asians in the U.S. reach leadership at higher rates than whites | A | — |
| 9.3 | East and Southeast Asian MBAs negotiate less and start with lower salaries | B | Own |
| 12.1 | Seeing a clear before-and-after example improves speaking | B | — |
| 12.2 | Recording and reviewing yourself helps, without raising anxiety | A | — |
| 12.3 | Practicing more doesn't automatically help; target one move | A+C | — |
| 12.4 | Cutting filler words alone doesn't make you more persuasive | B | Own |
| 12.5 | Feedback aimed at the person rather than the task often backfires | A | — |
| 13.1 | Spaced, retrieval-based practice lasts longer than cramming | A | — |
| 13.2 | Short videos are more engaging, but engagement isn't learning | B | — |
| 13.3 | Calling nerves "excitement" changes how you feel, not how you perform | B | — |
Claims we do not make
| Claim | Why not |
|---|---|
| "Your accent makes you less believable" | Replications are mixed, and the message causes harm (Ch. 8) |
| "Just add 'because' and people will agree" | Misreads the original study (Ch. 5) |
| "10,000 hours of practice makes an expert" | Contradicted by meta-analysis (Ch. 12) |
| "Say 'I'm excited' and you'll perform better" | The performance effect did not replicate (Ch. 13) |
| "People from culture X communicate like Y" | Country averages don't describe individuals (Ch. 9) |
| "If-then plans make you 65% more successful" | Misreads an effect size, and newer estimates are smaller (Ch. 7) |