Editing Observer-expectancy effect (section)

==Prevention==
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[[Double blind]] techniques may be employed to combat bias by causing the experimenter and subject to be ignorant of which condition data flows from.

It might be thought that, due to the [[central limit theorem]] of statistics, collecting more independent measurements will improve the precision of estimates, thus decreasing bias. However, this assumes that the measurements are statistically independent. In the case of experimenter bias, the measures share correlated bias: simply averaging such data will not lead to a better statistic but may merely reflect the correlations among the individual measurements and their non-independent nature.