search for: div898

NIST maintains a repository of Statistical Reference Datasets at http://www.itl.nist.gov/div898/strd/. I have been working through the datasets to compare R's results to their references with the hope that if all works well, this could become a validation package. All the linear regression datasets give results with some degree of accuracy except one. The NIST model includes 11 paramet...

Dear Users! I encountered with some problem in data reading while I challenged R (and me too) in a validation point of view. In this issue, I tried to utilize some reference datasets ( http://www.itl.nist.gov/div898/strd/index.html). And the result departed a bit from my expectations. This dataset dedicated to challenge cancellation and accumulation errors (case SmLs07), that's why this uncommon look of txt file. Treatment Response 1 1000000000000.4 1 1000000000000.3...

Hi all, I am a freshman of R,but I am interested in it! Those days,I am learning pages on NIST,with url http://www.itl.nist.gov/div898/handbook/eda/section3/probplot.htm, I am meeting a problem about probability plot and I don't know how to plot a data set with R. Could somebody tell me the answer,and a example is the best! I will look forward to your answer. Thank you very much.

...ve a question regarding the use of aov and lm-functions. I'm doing a fractional factorial experiment at our production site, and I need to familiarize myself with the analysis before I conduct the experiment. I've been working my way through the examples provided at http://www.itl.nist.gov/div898/handbook/pri/section4/pri472.htm http://www.itl.nist.gov/div898/handbook/pri/section4/pri472.htm , but I can't get the results provided in the trial model calculations. Why is this. Here is how I have tried to do it: > data.catapult=read.table("Fractional.txt",header=T) #Read the...

Hello, I am trying to test the precision of R on datasets from The Statistical Reference Datasets Project http://www.itl.nist.gov/div898/strd/index.html and I don't manage to understand how R is storing its results. For example, I calculate a mean on the michelso dataset (100 values) and find: > m=mean(michel) > m V1 299.8524 > print(m,digits=15) V1 299.8524 > print(m,digits=22) V...

...prueba de Thom para verificar su homogeneidad [0]. De momento me encuentro con los siguientes problemas: 1- ¿Existe la prueba de Thom en R? ¿O debo crearme mi propia función? 2- Para la realización del modelo senoidal estoy siguiendo los pasos que marcan en este texto: http://www.itl.nist.gov/div898/handbook/eda/section4/eda4253.htm pero me encuentro con los siguientes problemas: 1a - La serie que estoy utilizando tiene valores perdidos (ND) y hay varias funciones, como spectrum o lag.plot, que no se pueden utilizar. Yo los he reconvertido a 0, lo que no se si sera la correcto o me puede...

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Hello all - As I progress in R I am trying to automate functions I would have normally farmed out to Excel, SPSS or Statistica. Single factor anova is one of them. For example, a dataset from NIST StRD (http://www.itl.nist.gov/div898/strd/anova/AtmWtAg.html) has two groups: 1 2 107.8681568 107.8681079 107.8681465 107.8681344 107.8681572 107.8681513 107.8681785 107.8681197 107.8681446 107.8681604 107.8681903 107.8681385 107.8681526 107.8681642 107.8681494 107.8681365 107.8681616 107.8681151 107.86...

Hi, I'm interested in experimental design and data analysis on mixtures, like cake recipes where the sum of the components is fixed; e.g. <http://www.itl.nist.gov/div898/handbook/pri/section5/pri54.htm>. I can't believe that R doesn't have facilities to design and analyse such experiments, but I haven't been able to find them (I have looked quite hard!). Can anyone point me in the right direction? Thanks in advance, Keith Jewell mailto:k.jewell a...

The function wtd.var(x,w) in Hmisc calculates the weighted variance of x where w are the weights. It appears to me that wtd.var(x,w) = var(x) if all of the weights are equal, but this does not appear to be the case. Can someone point out to me where I am going wrong here? Thanks. Tom La Bone [[alternative HTML version deleted]]

...t. However the correlation line is parallel displaced depending on a clinical condition. I thought to a Tukey Mean Difference Plot would show me the difference betweenthe two values. I don't have the literature how the plot gets constructed, but my understanding from http://www.itl.nist.gov/div898/software/dataplot/refman1/auxillar/meandiff.htm is that the first from each distribution a qq plot is constructed and than the coardiantes of the qq-plot are transformed according the formula x=x+y/2 and y=x+y. I tried this with tmd(xyplot(a ~ b| c, data=data)) with a and b holding my log10 t...

...ow can I use chisq.test() as a goodness of fit test? Reading man-page I?ve some doubts that kind of test is available with this statement. Am I wrong? X2=sum((O-E)^2)/E) O=empirical frequencies E=expected freq. calculated with the model (such as normal distribution) See: http://www.itl.nist.gov/div898/handbook/eda/section3/eda35f.htm for X2 used as a goodness of fit test. Any help will be appreciated. Thank a lot. Bye. Vito ===== Diventare costruttori di soluzioni Became solutions' constructors "The business of the statistician is to catalyze the scientific learning process."...

Does anyone have code to plot bihistograms in R? See http://www.itl.nist.gov/div898/handbook/eda/section3/bihistog.htm for a description of a bihistogram. -- Hal Varian voice: 510-643-4757 SIMS, 102 South Hall fax: 510-642-5814 University of California hal at sims.berkeley.edu Berkeley, CA 94720-4600 http://www.sims.berkeley.edu/~hal

I'd like to generate some plots like you'd see on the old "normal probability graph paper", like the first plot in: <http://www.itl.nist.gov/div898/handbook/eda/section3/normprpl.htm> except the horizontal scale would have 1%, 5%, 25%, 50%, 75%, 95%, 99%, or similar quantiles, with associated tick/grid lines. [still hunting around for a good example...] something like these, but with the probability along the horizontal axis: <http:...

Hello all, Would somebody be kind enough to show me how to do a KS test in R for a lognormal distribution with ESTIMATED parameters. The R function ks.test()says "the parameters specified must be prespecified and not estimated from the data" Is there a way to correct this when one uses estimated data? Regards, Kwabena. -------------------------------------------- Kwabena Adusei-Poku

...kages to a certain number > of decimal places on some benchmark calculations. I don't know of any references, but maybe you can somehow "verify the accuracy of R" by running some analysis with the "NIST Statistical Reference Datasets"; the URL is http://www.itl.nist.gov/div898/strd/ So maybe you can run the analyses mentioned there and say that R (hopefully) returned the correct results. Hope this helps, Roland ---------- This mail has been sent through the MPI for Demographic Rese...{{dropped}}

Hi, Can anyone please provide the formula used to compute ACF(nlme). I believe the one that is used in R is of the type mentioned on the website. Please correct me if I am wrong. The normalization of the numerator (Ch) has been done by 'N' where as I would like to do it by 'N-k'. Is there anyway in the present implementation of ACF to normalize it by 'N-k', where

hi! I would like to ask help how to generate numbers from g-and-h distribution. This distribution is like normal distribution but span more of the kurtosis and skewness plane. Has R any package on how to generate them? Any help will be greatly appreciated. Thank you so much! Form, Filame Uyaco --------------------------------- [[alternative HTML version deleted]]

Dear Professor I have read your questions in the website on Doubly non-central F-distribution. I am looking for source code for evaluating this function now. I have matlab code but it's only accurate up to the 4th decimal point. Dataplot is more accurate, but it is not user friendly as you only can evaluate one function at a time. So I would like to know do you have found any R code for

...fairly new to R and am trying to expand my knowledge beyond using R for simple summary statistics and basic tests. To that end I am attempting to write an interactive R-script that will perform a general rational function fit to a given dataset based on the example given at http://www.itl.nist.gov/div898/handbook/pmd/section6/pmd64.htm. The problem that I seem to have is that the fitted function is nearly identical to the NIST results when I use their initial values (these are representative values that are close to actual data, but not taken from the dataset) for generating the starting point for...

...half-knowledge that I have is often sufficient to see that many otherwise nice sources of statistical knowledge are dangerously incomplete when it comes to explaining the preconditions required for applying a certain technique (One example: The extensive NIST handbook at http://www.itl.nist.gov/div898/handbook/ fails to mention that the Wilcoxon rank sum test assumes a continuous distribution underlying the sample) This is not to speak of how to correctly interpret the results. My situation is this: - I often have a hard time understanding the R documentation due to lack of background. - I a...