The difference was around 0.8 seconds. Kinnebrooke was sacked, Maskelyne claiming he had ' fallen into some irregular and confused method of his own '. Neville Maskelyne wrote up his experiences in ' Astronomical Observations at Greenwich' ' but did not appreciate the significance of the finding. Bessel went on to calibrate individual observers, deriving 'personal equations' which compensated for their individual differences. It is not only individual observers or subjects who have biases that can influence measurements.
Experimenters can also influence results either deliberately or accidentally.
The volume of skulls was measured by filling them with seed, which was then weighed. The experimenter had certain preconceptions about skull volume, so would be a bit more enthusiastic about packing seed into skulls which he thought should be big. This introduced a systematic bias in the volume measurements. His owner, Wilhelm von Osten, claimed that his horse could answer a wide variety of questions, such as solving mathematical problems and telling the time, and communicate the answers using hoof-taps. Prominent German scientists tested Clever Hans until most were convinced that the horse's highly accurate responses were not the result of trickery.