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==Information bias==
==Information bias==
Information bias results from errors in measurement or classification of exposures or outcomes of interest amongst the individuals included in the study. In the case of analytic studies, this may be classified as '''differential''' or '''non-differential''':<br>
Information bias results from errors in measurement or classification of exposures or outcomes of interest amongst the individuals included in the study. In the case of analytic studies, this may be classified as '''differential''' or '''non-differential'''. Non-differential bias will tend to reduce the strength of any association present, and will increase the probability of a [[Random variation#Hypothesis testing and study power|type II error]], whereas the effect of differential bias cannot be predicted.<br>
Non-differential bias will tend to reduce the strength of any association present, and will increase the probability of a [[Random variation#Hypothesis testing and study power|type II error]], whereas the effect of differential bias cannot be predicted.
===Non-differental information bias/Measurement error===
===Non-differental information bias/Measurement error===
Non-differential bias occurs when the chance of bias is not affected by the group the individuals belong to. '''Measurement error''' is a common example of non-differential bias - for example, if scales are not correctly calibrated, they may incorrectly record the weight of all items weighed, regardless of their 'exposure' status.
===Differential information bias===
===Differential information bias===
Differential bias occurs when the chance of bias is different for the different groups being compared. For example, Boxer dogs may be more likely than other dog breeds to be diagnosed as having mast cell tumours, even if they do not have them, due to a postulated breed predisposition.
[[Category:Veterinary Epidemiology - General Concepts|I]]
[[Category:Veterinary Epidemiology - General Concepts|I]]