The crucial characteristic of the EEV approach is that it does not incorporate a systematic preference for better-grounded estimates over rougher estimates. It ranks charities/actions based simply on their estimated value, ignoring differences in the reliability and robustness of the estimates.

Uncertainty in estimates of the expected value of an intervention tend to have the effect of naturally reducing it - since there are may ways to fail and few ways to succeed.

For instance think about drug trials. If someone claims that their results say there's a 50% chance of the drug curing a disease, and there's a 50% chance that they got their results muddled up with those of some different drug, that often makes the expected value of the treatment fall to around 25% - since most drugs don't work.