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INTRODUCTION

Test Taking Tips

  • Memorize the following table for easy calculation of sensitivity, specificity, and positive and negative predictive values.

  • Know the differences between different types of statistical tests.

  • Not a lot changes in statistics, so similar questions are phrased differently annually.

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What is sensitivity?

  • The proportion of truly diseased persons in a screened population who are identified as being diseased by the test. It is a measure of the probability of correctly diagnosing a condition.

What is the sensitivity equation?

  • True positive / (true positive + false negative)

What is specificity?

  • The proportion of truly nondiseased persons who are so identified by the screening test

What is the specificity equation?

  • True negative / (false positive + true negative)

What is the false-positive rate?

  • 1 – specificity

What is the false-negative rate?

  • 1 – sensitivity

What is the positive predictive value?

  • The probability that a person with a positive test result has the disease

What is the positive predictive equation?

  • True positive / (true positive + false positive)

What is the negative predictive value?

  • The probability that a patient with a negative test result really is free of the disease

What is the negative predictive value equation?

  • True negative / (false negative + true negative)

What is the definition of prevalence?

  • The total number of cases of a given disease in a specified population at a designated time

What is the definition of incidence?

  • The number of new cases of a given disease during a given period in a specified population

What is the absolute risk reduction?

  • The absolute arithmetic difference in outcome rates between control and experimental patients in a trial

What is the relative risk reduction?

  • The proportional reduction in outcome rates between control and experimental patients in a trial

A range of values that has a specified probability of containing the rate or trend is called what?

  • Confidence interval

A method of studying a drug or procedure in which both the subjects and investigators are kept unaware of who is actually getting which specific treatment is called what?

  • Double-blind method

The number of patients who need to be treated to prevent one adverse outcome is known as what?

  • Number needed to treat

The probability that ...

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