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Drug Trials: Sample Size Requirement

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A drug manufacturer wants to estimate the effect of its new drug designed to increase patients white blood cell count. How many sample runs of the drug must be performed to ensure that the estimate is accurate to within 50 cells (per microliter of blood) at 95% confidence? Assume the population standard deviation to be 110 cells.

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Sample size requirements for drug trials are examined.

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The margin of error ME<=50, the population standard deviation sigma=110 cells. For 95% confidence, z=1.96. So, we use a ...

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  • BSc , Wuhan Univ. China
  • MA, Shandong Univ.
Recent Feedback
  • "Your solution, looks excellent. I recognize things from previous chapters. I have seen the standard deviation formula you used to get 5.154. I do understand the Central Limit Theorem needs the sample size (n) to be greater than 30, we have 100. I do understand the sample mean(s) of the population will follow a normal distribution, and that CLT states the sample mean of population is the population (mean), we have 143.74. But when and WHY do we use the standard deviation formula where you got 5.154. WHEN & Why use standard deviation of the sample mean. I don't understand, why don't we simply use the "100" I understand that standard deviation is the square root of variance. I do understand that the variance is the square of the differences of each sample data value minus the mean. But somehow, why not use 100, why use standard deviation of sample mean? Please help explain."
  • "excellent work"
  • "Thank you so much for all of your help!!! I will be posting another assignment. Please let me know (once posted), if the credits I'm offering is enough or you ! Thanks again!"
  • "Thank you"
  • "Thank you very much for your valuable time and assistance!"
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