Experimental science demands repeatability of results but many experiments are not due to fraud or error.[1][2] The list of papers whose results were later retracted or discredited, thus leading to invalid science is growing.[3] Some errors are introduced when the experimenter's desire for a certain result unconsciously influences selection of data (a problem which is possible to avoid in some cases with double-blind protocols).[4] There have also been cases of deliberate scientific misconduct.[5]