Changes

These ratio measures of strength of association vary from approximately 0 to +∞, with an estimate of 1 indicating no association. It should be noted that although the odds ratio for disease is a useful measure of strength of association, its value will differ from the equivalent prevalence or risk ratio, with a tendency towards more extreme (more positive in the case of prevalence/risk ratios greater than 1, or smaller in the case of prevalence/risk ratios less than 1) values when the disease under investigation is common in the population. This may not be a problem when using case control studies, as these are often used when the disease in question is rare. However, odds ratios are commonly used in more advanced statistical methods (particularly [[Logistic regression|logistic regression]] - in which case, care must be taken when interpreting odds ratios.

These ratio measures of strength of association vary from approximately 0 to +∞, with an estimate of 1 indicating no association. It should be noted that although the odds ratio for disease is a useful measure of strength of association, its value will differ from the equivalent prevalence or risk ratio, with a tendency towards more extreme (more positive in the case of prevalence/risk ratios greater than 1, or smaller in the case of prevalence/risk ratios less than 1) values when the disease under investigation is common in the population. This may not be a problem when using case control studies, as these are often used when the disease in question is rare. However, odds ratios are commonly used in more advanced statistical methods (particularly [[Logistic regression|logistic regression]] - in which case, care must be taken when interpreting odds ratios.

[[Category:Veterinary Epidemiology - Statistical Methods|B]]

[[Category:Veterinary Epidemiology - Statistical Methods|C]]