Introductory Biostatistics
Example 12.9 Suppose that in Example 12.8, the researcher wanted to design a study such that its power to detect a di¤erence bet ...
HA:p 1 <p 2 or p 10 p 2 How large a total sample should be used to conduct this vaccine study? Suppose that it is important t ...
Example 12.11 A new vaccine will be tested in which subjects are to be randomized into two groups of equal size: a control (unim ...
survival rates. The comparision of the five-year survival rate from an experi- mental treatment versus the five-year survival ra ...
tigators hope to increase this to at least 70% using intravesical chemotherapy (treatment by drug) immediately after surgery at ...
12.10 SAMPLE SIZE DETERMINATION FOR CASE–CONTROL STUDIES In a typical case–control study, cases of a specific disease are ascert ...
where p 1 ¼ yp 0 1 þðy 1 Þp 0 The problem is more complicated if we plan for groups with unequal sample sizes. First, we have t ...
and from p¼ 0 : 3 þ 0 : 5625 2 ¼ 0 : 4313 a¼ 0 : 05 !z 1 a¼ 1 : 96 ðtwo-sided testÞ b¼ 0 : 10 !z 1 b¼ 1 : 28 we obtain a requi ...
the exposure histories of the case and his or her matched control are di¤erent. We have to go through two steps, first to calcul ...
a¼ 0 : 05 !z 1 a¼ 1 : 96 ðtwo-sided testÞ b¼ 0 : 10 !z 1 b¼ 1 : 28 The number of discordant pairs is given by P¼ y 1 þy ¼ 0 : ...
di¤erent way, besides the level of significanceaand the desired powerð 1 bÞ, the required total sample size depends on the rati ...
the total sample sizeNis given by N¼ 1 ðlnyÞ^2 1 w 1 þ 1 w 0 ðz 1 aþz 1 bÞ^2 For example, if we want the size of the contro ...
EXERCISES 12.1 Some opponents of the randomized, double-blinded clinical trial, espe- cially in the field of psychiatry, have ar ...
12.9 Refer to Example 12.12. Find the total sample size needed if we retain all the specifications except that the hypothesized ...
dence? (Use a conservative estimate because no prior estimate of the prevalence in this city is assumed available.) (b)A similar ...
How large should a total sample size be if we decide to preseta¼ 0 : 01 and that it is important to detect an LDL cholesterol le ...
prevention, reduction, or mitigation of drug-related toxicity. This new agent is to be tested against a placebo in a double-blin ...
12.27 A phase III double-blind randomized trial is planned to compare a new drug versus placebo as adjuvant therapy for the trea ...
purpose of examining the nodes and removing tissue samples to exam- ine under the microscope for evidence of cancer. However, ce ...
Bibliography Agresti, A. (1990).Categorical Data Analysis. New York: Wiley. Ahlquist, D. A., D. B. McGill, S. Schwartz, and W. F ...
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