Mammography is the process of using low-energy X-rays as an early detection meth

Question

Mammography is the process of using low-energy X-rays as an early detection method for breast cancer. While the test is widely used, it is not perfect, and may occasionally result in false positives or false negatives. You perform a study that compares mammography to a breast tissue biopsy, which is considered the gold standard in breast cancer detection. Of the 1000 females you sample, 950 mammographies were negative. Of these 950 women, the tissue biopsy confirmed the absence of cancer in 935 women. However, 15 of these 950 women had positive tissue biopsies. 43 of the 50 women who had positive mammographies also had positive tissue biopsies.

How many false positives and false negatives were there in this study?

What is the sensitivity of this test?

What is the specificity of this test?

What is the positive predictive value (PPV) of this test?

What is the accuracy of the test?

What is the prevalence of the condition?

Given the same sensitivity and specificity, what would happen to the positive predictive value (PPV) if the prevalence of the condition increased?

Explanation / Answer

1. False positives= 7.(50 Total positives - 43 confirmed positives=7 false positives)

False negatives = (950 Total negatives - 935 confirmed negatives = 15 false negatives)

2. Sensitivity- true positive rate = 43/50*100= 86%

3. Specificity- true negative rate = 935/950*100 = 98.42%

4. Prevalence = 43+15= 58

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