Counterfactual questions are among the most important topics in business. I hear companies asking this kind of questions all the time. Afterward, the average user spending was 100 $. But how do we know what they would have spent if we didn't do our action?" These problems are usually addressed through A/B testing.

NASA presents its space explorers as instant legends, in any event, when their achievements in space are groundbreaking. Maybe the best case of NASA's public-relations prowess was the participation of John Glenn, the first American to circle Earth, in the 1998 shuttle mission STS-95. Glenn's re-visitation to space at the age of 77 made STS-95 the most ardently followed mission since the Apollo moon arrivals. NASA guaranteed that Glenn went up for science, he filled in as a test subject in different clinical trials, however, unmistakably the primary advantage of Glenn's space shuttle ride was exposure, not a scientific revelation. NASA is as yet leading grade A science in space, but it is being finished by unmanned probes instead of space explorers.