Dear Chegg Expert, Can you please help me with the question below. I always stru

Question

Dear Chegg Expert, Can you please help me with the question below. I always struggle setting up the 2x2 charts so it would be helpful if you set up the table and show me how to work the calculations. I do know that the PPV is 33.56 and the NPV is 99.98 if this is helpful to you. Thanks in advance, Shani St. Broncoville Regional Medical Center is evaluating a new rapid methicillin-resistant streptococcus aureus (MRSA) wound culture test which can be performed in-house rather than sent out to the reference laboratory in Capitol City. It takes three days for the MRSA wound culture to return from the reference laboratory (considered the gold standard) and costs $100. The new test kit takes 24 hours to rule out MRSA and costs $50. The new rapid test is 99.2% sensitive and 96% specific. The prevalence of wounds infected with MRSA in your population is 296 per 10,000 persons. Develop a 2 x 2 table. 1. Calculate the Positive Predictive Value (PPV) for the new test kit 2. Calculate the Negative Predictive Value (NPV) for the new test kit Enter only numbers into your answer. Round to two decimal places after completing mathematical operations. Express your answer as a percent but do NOT place a % sign after your answer.

Explanation / Answer

For the new test kit, sensitivity = 99.2%

specificity = 96%

Let us try to understand how the 2x2 table is made

First enter the total value in the box corresponding to 4th column and 4th row

Then multiply prevalance with total and write in 4th row 2nd colum

Wound infected with MSRA and test positive = 200xsensitivity

= 200x0.992

= 198

PPV = 198/590 x100

= 33.56

NPV = 9408/9410 x 100

= 99.98

Wound infected with MRSA Wound not infected with MSRA Total Positive 198 9800-9408 = 392 590 Negative 200 - 198 = 2 9800x0.96 = 9408 9410 Total 0.02x10,000 = 200 10,000-200 = 9800 10,000

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