simple Q: required sample size & usage of power.t.test()
Hi community, Seems I am too stupid: I try to calculate with power.t.test() an example from the statistics textbook [Jerrold H. Zar, Biostatistical Analysis, 2nd edition, Prentice Hall, 1984, Chapter 8, Exercise 8.4, (page 120)]: ------- A sample of size 18 has a mean of 13.55cm and a variance of 6.4512cm^2. (a) Calculate the 95% confidence interval for the population mean. (b) How large a sample would have to be taken from this population to estimate µ to within 1.00cm, with 95% confidence? (c) 2.00cm with 95% confidence? (d) 2.00cm with 99% confidence? Result should be - according to the answers appendix - (a) 13.55 +- 1.26cm (b) n=29, (c) n=10, (d) n=11 ------- Here my questions: (1) which functions in R can be used to solve (a) (2) what has to be the syntax to answer (b), (c) and (d) ? Thanks in advance, Osiander
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