Experimenter bias

Biasing effect on the results of experiments caused by expectations or preconceptions on the part of researchers, such effects may be due to unconscious slanting of research procedures, flawed interpretation of events and of data, or inaccurate reporting in the direction of the (favoured) hypothesis.

Other complications include: slight, but consistent time-recording errors or errors of measurement, leanings in giving ratings, errors in entering or transcribing data, and the drawing of unsubstantiated conclusions, either singly or in combination, which may tip the scale in favour of the preferred hypothesis.

(see also: science, experimental research, control group, double-blind, randomized assignment, confound/confounding, variable, correlation, Observer effect»Observer bias, wishful thinking)