# Project #62871 - Biostatistics

Calculate the following probabilities for a patient about to undergo CABG ( coronary-artery bypass graft) surgery.

The only possible, mutually exclusive outcomes of the surgery are death, relief of symptoms, ( angina, dyspnea), or continuation of symptoms. The probability of death is 0.02 and the relief of symptoms is 0.80. What is the probability that the patient will continue to have symptoms?

Two known complications of heart surgery are stroke and heart attack, with probability of 0.02 and 0.05, respectively. The patient asks what chances he has of having both the complications. Assume that the complications are conditionally independent, and calculate your answer.

The patient wants to know the probability that he will have the stroke given that has a heart attack as a complication of surgery. Assume that 1 in 500 patients has both complications, that the probability of heart attack is 0.05 and that the events are independent. Calculate your answer.

You are concerned that a patient with sore throat may have a bacterial infection that would require antibiotic therapy (as opposed to viral infection, for which no treatment is available). Your treatment threshold is 0.8, and based on the examination you estimate the of bacterial infection as 0.6. A test is available with the TPR = 0.75 and TNR = 0.85, that indicates the presence and absence of the bacterial infection. State how would you adjust the posttest probability after the positive test result.

In a certain hospital there are 360 patients, 40 of whom have clinically proven cirrhosis of the liver. An expert in abdominal palpation determines that 32 out of 360 patients have palpable spleens, of whom 16 have cirrhosis. In this hospital:

a. What is the sensitivity, and the specificity of palpable splenomegaly for cirrhosis?

b. What is the predictive value for cirrhosis in a patient with palpable splenomegaly?

c. What is the probability that a different problem exists in those with palpable spleens?

d. Is the presence of a palpable spleen a good clue for cirrhosis/

e. What is the probability that a patient whose spleen is not palpable does not have cirrhosis?

What percentage of patients, with cirrhosis, have palpable spleens? What percentage do not have palpable spleens?

 Subject Medicine Due By (Pacific Time) 03/18/2015 12:00 am
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