External validity
How far a study's result can be carried outside the exact conditions in which it was tested: to other people, other tasks and other settings.
In plain English
Every study has its own setting: who took part, what they did, what was measured and when. A result can be perfectly correct inside that setting and still say little about anything else. Before applying a finding, compare the original test with your situation: the people, the task, the stakes. The further apart they are, the less the number tells you.
Uncle Gary explains
The '7% words, 38% tone, 55% body language' rule comes from 1967 experiments in which students judged liking from single words such as 'maybe'. Kevin's boss applied it to the annual budget presentation, which he gave in silence.
Why it matters for your money
A pattern found in one market, one decade or one kind of stock is often quoted as a law of investing. Check whether it was ever tested anywhere else.
Where we tested it
Related terms
All glossary terms. Educational content, not financial advice.