Assuming the days of raining during half a year of all states(provinces) of a country is normally distributed (mean=�, standard deviation=�) with sigma (�) equals to 2. We now have 10 data points here: 26.64, 30.65, 31.27, 33.04, 32.56, 29.10, 28.96, 26.44, 27.76, 32.27. Try to get the 95% level of CI for �, using parametric Bootstrap method with bootstrap size B=8000.
my code - what am i doing wrong #set sample size n, bootstrap size B n = 10 b = 8000 set a vector of days of rain into "drain" drain = c(26.64, 30.65, 31.27, 33.04, 32.56, 29.10, 28.96, 26.44, 27.76, 32.27) #calculate mean of the sample for days of rain mdr=mean(drain) mdr #calculate the parameter of the exponential distribution lambdahat = 1.0/mdr lambdahat #draw the bootstrap sample from Exponential x = rexp(n*b, lambdahat) x bootstrapsample = matrix(x, nrow=n, ncol=b) bootstrapsample # Compute the bootstrap lambdastar lambdastar = 1.0/colMeans(bootstrapsample) lambdastar # Compute the differences deltastar = lambdastar - lambdahat deltastar # Find the 0.05 and 0.95 quantile for deltastar d = quantile(deltastar, c(0.05,0.95)) d # Calculate the 95% confidence interval for lambda. ci = lambdahat - c(d[2], d[1]) ci [[alternative HTML version deleted]] ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. |
> On Dec 7, 2017, at 2:51 PM, Stephanie Tsalwa <[hidden email]> wrote: > > Assuming the days of raining during half a year of all states(provinces) of a country is normally distributed (mean=�, standard deviation=�) with sigma (�) equals to 2. We now have 10 data points here: 26.64, 30.65, 31.27, 33.04, 32.56, 29.10, 28.96, 26.44, 27.76, 32.27. Try to get the 95% level of CI for �, using parametric Bootstrap method with bootstrap size B=8000. This has the definite appearance of a homework assignment. It also has several other features which likewise suggest a failure to read the Posting Guide, a link to which is at the bottom of every posting sent out from the Rhelp mail-server. You are advised to post credential/affiliation information and more context of the wider goals if my assumption of HW-status is incorrect. -- David. (And yes I do realize that I am also not posting any affiliation information, either, but I'm retired and am not asking for free advice, am I? Don't follow my bad example.) > > my code - what am i doing wrong > > #set sample size n, bootstrap size B > n = 10 > b = 8000 > > > set a vector of days of rain into "drain" > drain = c(26.64, 30.65, 31.27, 33.04, 32.56, 29.10, 28.96, 26.44, 27.76, 32.27) > > #calculate mean of the sample for days of rain > mdr=mean(drain) > mdr > > #calculate the parameter of the exponential distribution > lambdahat = 1.0/mdr > lambdahat > > #draw the bootstrap sample from Exponential > x = rexp(n*b, lambdahat) > x > > bootstrapsample = matrix(x, nrow=n, ncol=b) > bootstrapsample > > # Compute the bootstrap lambdastar > lambdastar = 1.0/colMeans(bootstrapsample) > lambdastar > > # Compute the differences > deltastar = lambdastar - lambdahat > deltastar > > # Find the 0.05 and 0.95 quantile for deltastar > d = quantile(deltastar, c(0.05,0.95)) > d > > # Calculate the 95% confidence interval for lambda. > ci = lambdahat - c(d[2], d[1]) > ci > > > [[alternative HTML version deleted]] > > ______________________________________________ > [hidden email] mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. David Winsemius Alameda, CA, USA 'Any technology distinguishable from magic is insufficiently advanced.' -Gehm's Corollary to Clarke's Third Law ______________________________________________ [hidden email] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. |
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