Scientific integrity

"Integrity is doing the right thing, especially when no one is watching." (Wikipedia)

Scientific integrity refers to honest and transparent methods and reporting of research. In other words, there is no cooking the books or even subtly influences of bias to privilege some lines of investigation or results over others. There is no falsification or fabrication or plagiarism.

What are some examples of compromised scientific integrity?
 * 1) Witholding of politically unwanted results