* Individual and group level test characteristics (sensitivity and specificity) are not equivalent.
* Individual and group level test characteristics (sensitivity and specificity) are not equivalent.
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* <nowiki>The number of animals to be tested in the group (sample size) is relatively independent of group size except for small groups (<~1000) or where sample size is more than about 10% of the group size. Alternative methods are available for small populations or where sample size is large relative to group size.</nowiki>
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* The number of animals to be tested in the group (sample size) is relatively independent of group size except for small groups (<~1000) or where sample size is more than about 10% of the group size. Alternative methods are available for small populations or where sample size is large relative to group size.
* The number of animals required to be tested in the group depends much more on individual animal specificity than it does on sensitivity.
* The number of animals required to be tested in the group depends much more on individual animal specificity than it does on sensitivity.
* The number of animals to be tested in the group is linearly and inversely related to the expected prevalence of infected animals in the group.
* The number of animals to be tested in the group is linearly and inversely related to the expected prevalence of infected animals in the group.
Revisi terkini pada 10 Mei 2015 14.38
Individual and group level test characteristics (sensitivity and specificity) are not equivalent.
The number of animals to be tested in the group (sample size) is relatively independent of group size except for small groups (<~1000) or where sample size is more than about 10% of the group size. Alternative methods are available for small populations or where sample size is large relative to group size.
The number of animals required to be tested in the group depends much more on individual animal specificity than it does on sensitivity.
The number of animals to be tested in the group is linearly and inversely related to the expected prevalence of infected animals in the group.
As the required level of statistical confidence increases, so the required sample size increases. The usual level is 95%. If this is increased to 99%, there is an approximate increase of 50% in the required sample size. For a reduction from 95% to 90% confidence, there is a decrease in sample size by 25%.
As the sample size increases, group level sensitivity increases.
As the number of animals used to classify the group as positive is increased, there is a corresponding increase in specificity.
As group level sensitivity increases, group level specificity decreases.
When specificity = 100% at the individual animal level, all uninfected groups are correctly classified i.e. group level specificity also equals 100%.
