Imagine a scientist who does an experiment, and doesn't like the results. Perhaps the scientist had hoped to see a certain pattern of findings and is disappointed that it's not there.
Suppose that this scientist therefore decided to manipulate the data. She goes into the spreadsheet and adds new, made-up data points, until she obtains a statistically significant result she likes, and publishes it. That's bad. Now, start this scenario over. Suppose that rather than making up data, the scientist throws it out. She runs the experiment again and again (without changing it), throwing out the results every time they're wrong, until eventually, by chance, she obtains a statistically significant result she likes, and publishes it. Is that bad? Yes, but isn't it less obviously bad than data fabrication? I'm talking about an intuitive level. We feel that fabrication is clearly outrageous, fraudulent. Cherry-picking is bad, no-one denies it, but ...
