A meta-analysis pools ten studies of 40 participants each and reports a precise overall effect. Why does pooling not automatically make the conclusion more trustworthy than the individual studies?

C. Because it inherits whatever is wrong with its inputs.

Pooling improves precision, which is not accuracy, narrowing an interval helps only if the estimate is aimed at the right place. If the ten available studies are the significant survivors of thirty, pooling locates the literature's inflated estimate with impressive confidence. The specific danger is that the garbage comes out looking more authoritative than it went in.