Stefan Tigges on Radiopaedia.org

Stefan Tigges

Professor of Radiology, Emory University School of Medicine

Thoracic Radiologist interested in education and using comics/drawing to teach. No pharmaceutical or medical device conflict of interest.

Disclosures:
  • Nothing to disclose
169 results found
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Question 2885

In the 1960s, the Health Insurance Plan of New York studied the efficacy of mammography for breast cancer detection. In their trial, there were 132 true positive, 47 false negative, 985 false positive and 62,295 true negative mammograms. What was the negative predictive value of mammography?

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Question 2901

How are odds of an “event” calculated?

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Question 2902

What are the odds of rolling a 4 or a 5 with a fair 6-sided die?

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Question 2903

The odds of an event occurring are 1. What is the probability of that event occurring?

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Question 2904

What is the definition of a likelihood ratio?

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Question 2905

Which of the following is the formula for a negative likelihood ratio?

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Question 2906

A diagnostic test has a sensitivity of 90% and a specificity of 90%. What is the positive likelihood ratio?

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Question 2907

A diagnostic test has a sensitivity of 90% and a specificity of 90%. What is the negative likelihood ratio?

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Question 2908

What is the best interpretation of a positive likelihood ratio of 10?

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Question 2909

What is the best interpretation of a negative likelihood ratio of 0.1?

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Question 2910

Which of the following is the formula for a positive likelihood ratio?

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Question 2912

How is the number needed to screen calculated?
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Question 2913

When can the odds ratio be used as an approximation of the risk ratio?

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Question 2914

What is the definition of statistical risk?

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Question 2915

When are rate ratios used instead of risk ratios?

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Question 2916

What is the best interpretation of a risk ratio, rate ratio or odds ratio that is <1?

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Question 2917

What is the most appropriate measure of association for a cohort study where subjects are followed for 3 months?

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Question 2918

What is the most appropriate measure of association for a cohort study where subjects are followed for 30 years?

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Question 2919

What is the most appropriate measure of association for a case control study?

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Question 2922

A case control study shows an association between birth order and Down syndrome, with higher odds of Down syndrome with later births. What is the most likely source of confounding in this study?