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What is the formula for sensitivity?
Sensitivity = TP/(TP + FN)

What is the formula for specificity?
Specificity = TN/(TN + FP)

What is Positive Predictive Value?
 what proportion of positive results are true
 PPV = TP/(TP + FP)

What is Negative Predictive Value?
 what proportion of those with a negative test do no have the disease
 NPV = TN/(TN + FN)

What is Accuracy?
 the total percentage that is correctly selected  whether positve or negative
 Accuracy = (TP + TN) / total screened patients

What is reliability?
ability of a test to measure something consistently

What type of bias is present when you have used only hospital records to estimate population prevalence?
Berkson Bias

What type of bias occurs when information is gathered in a manner that distorts the information?
Hawthorne Effect

What statistic do we use in crosssectional studies?
Chisquare

What is Relative Risk?
 it compares the incidence in the exposed group to the unexposed
 RR = exposed with disease / unexposed with disease

What is Attributable Risk?
 deals with absolute numbers;
 how many more cases in the exposed group than the unexposed?
 AR = exposed with disease  unexposed with disease

What is the Number Needed to Treat?

What the heck is an Odds Ratio?
 used in casecontrol studies, estimates the strength of a risk factor
 if someone has the disease, what are the odds that they had the risk factor?
 OR = product of trues / product of falses

