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Chapter 4: Q9P (page 92)
What is the meaning of a confidence interval?
Thus, the specific probability, an interval that contains the accepted/true value (confidence level).
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A reliable assay shows that the ATP (adenosine triphosphate) content of a certain cell type is. You developed a new assay, which gave the values117,119,111, 115, 120(average = 116.4) for replicate analyses. Do your results agree with the known value at the 95%confidence level?
List the three different cases that we studied for comparison of means, and write the equations used in each case.
Blood plasma proteins of patients with malignant breast tumors differ from proteins of healthy people in their solubility in the presence of various polymers. When the polymers dextran and poly(ethylene glycol) are mixed with water, a two-phase mixture is formed. When plasma proteins of tumor patients are added, the distribution of proteins between the two phases is different from that of plasma proteins of a healthy person. The distribution coefficient ( K) for any substance is defined as K =[concentration of the substance in phase[concentration of the substance in phase B ]. Proteins of healthy people have a mean distribution coefficient of 0.75 with a standard deviation of 0.07. For the proteins of people with cancer, the mean is 0.92 with a standard deviation of 0.11.
(a) Suppose that Kwere used as a diagnostic tool and that a positive indication of cancer is taken as. What fraction of people with tumors would have a false negative indication of cancer because?
(b) What fraction of healthy people would have a false positive indication of cancer? This number is the fraction of healthy people with, shown by the shaded area in the graph below. Estimate an answer with Table 4 - 1 and obtain a more exact result with the NORMDIST function in Excel.
(c) Vary the first argument of the NORMDIST function to select a distribution coefficient that would identify 75% of people with tumors. That is, 75% of patients with tumors would have K above the selected distribution coefficient. With this value of K, what fraction of healthy people would have a false positive result indicating they have a tumor?
A straight line is drawn through the points , and to give , , and . Express the slope and intercept and their uncertainties with reasonable significant figures.
Use the NORMDIST spreadsheet function to answer these questions about the brakes described in Exercise 4-C:
(a) What fraction of brakes is expected to be 80% worn in less than 45800miles?
(b) What fraction is expected to be 80%worn at a mileage between 60000and 70000miles?
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