# Disease incidence and prediction. Flashcards

Tests that define an exposure or a disease status are subjected to what sort of error?

Systematic and random error.

Is random or systematic error important in regards to bias?

Systematic.

What two things can result in information bias?

- Imperfect definitions of study variables.

2. Flawed data collection procedures.

What can information bias result in?

Misclassification of exposure or disease.

What two types of misclassification bias exist?

- Non differential.

2. Differential.

What sort of bias exhibits bias towards the null (in terms of the Odds Ratio)?

Non differential.

Misclassification bias is similar but different to information bias. True or false?

False, misclassification bias is a type of information bias.

Is the OR higher, lower, the same, or both in differential misclassification bias?

Both, it can be higher or lower.

Define non differential misclassification bias.

The same amount of bias towards exposed/ non exposed state is the same in both the cases and control group.

Define differential misclassification bias.

The same amount of bias towards exposed/ non exposed state is different in the cases and control group.

What defines the ‘True status’ of a disease when testing a new diagnostic test?

The current gold standard test.

Define sensitivity.

Proportion of individuals with a disease which test positive.

Define specificity.

Proportion of those without a disease who tested negative.

What is the equation for sensitivity?

TP/(TP+FN)

What is the equation for specificty?

TN/(TN+FP)

What is the equation for false positivity rate?

FP/(FP+TN) –> FP/ all non diseased

What is the equation for false negative rate?

FN/(FN+TP) -> FN/ all diseased

Define ‘Positive Predictive Value’ (PPV).

Proportion of positive tests that correctly identify diseased individuals.