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paulvonhippel (114) 67 Articles, 47 Replies, 114 Points

Since 4/14/2012 2:55:23 AM, paulvonhippel has written 67 articles and participated in 47 conversations.
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paulvonhippel

paulvonhippel's articles:
 Items(67) /7 Next >> Last >| Moment's of student's t distribution 4 3 (3/30/2013 8:06:40 AM) comp.soft-sys.math.mathematicaI'm trying to get a general formula for the moments of a non-standardized t distribution. When I ask for the moments in general -- Moment[StudentTDistribution[\[Mu], \[Sigma], \[Nu]], k] -- Mathematica me...paul Mode of InverseChiSquareDistribution 0 17 (11/13/2012 5:12:45 AM) comp.soft-sys.math.mathematicaAs a first step toward solving a more complicated problem, I would like to calculate the mode of the InverseChiSquareDistribution with D-1 degrees of freedom. The answer is 1/(D+1) but I am having trouble getti...paul Non-estimable combination in PROC MIXED 0 33 (11/7/2012 9:12:18 PM) comp.soft-sys.sasI am having a little trouble understanding what makes a linear combination = non-estimable in PROC MIXED. Here is a simplified version of my problem. Su= ppose I am predicting test scores with a RACE variable...Paul IOTF/WHO obesity threshholds 1 37 (7/2/2012 10:18:29 PM) comp.soft-sys.sasIs there SAS code for calculating whether a child is overweight under the IOTF or WHO standards? I have already found code for the CDC standards.... ...Paul Moment function 0 35 (6/20/2012 7:50:29 AM) comp.soft-sys.math.mathematicaI would like a formula for the mth moment of Z^p, where Z~Normal(mu,sigma) and p is a positive integer. With m=p=1, the answer should be mu -- i.e., the first moment of a normal variable is the mean mu. But tha...paul power of logistic distribution 0 38 (6/17/2012 8:00:04 AM) comp.soft-sys.math.mathematicaI would like an expression for the mean of a variable that is some integer power of a logistic variable. I have tried the following approach, which did not work. Many thanks for any suggestions. Here is what...paul Bug in PROC LIFEREG with DIST=LOGNORMAL 0 27 (6/3/2012 10:26:48 AM) comp.soft-sys.sasI believe I have found a bug in PROC LIFEREG using DIST=LOGNORMAL. The program appears to incorrectly exclude any rows where the lower censoring point is zero. Here is an example. data test; input bin_mi...Paul PROC IML: test for positive definiteness 3 39 (5/24/2012 7:33:18 PM) comp.soft-sys.sasIs there a single PROC IML function that will tell me whether a matrix is p= ositive definite? Similarly, is there a function that will tell me which of= a set of matrices (A,B,C) is largest in the sense tha...Paul Truncated inverse Wishart distribution 0 31 (5/21/2012 9:57:34 AM) comp.soft-sys.math.mathematicaI would like to calculate the mean of a truncated inverse Wishart distribution? I.e., if B is an inverse Wishart variable, then I'd like to calculate E(B|B

paulvonhippel's replies:
 Items(22) /3 Next >> Last >| Grouping terms under the radical 5 27 (7/7/2011 11:47:06 AM) comp.soft-sys.math.mathematicaThis must be a classic question. When I input Sqrt[(2 n)] Mathematica displays the output as Sqrt[2] Sqrt[n] -- i.e., both 2 and n are under their own radical. The display of output doesn't change if I imp...paulvonhippel (114) Stacked fractions 4 33 (7/7/2011 11:47:36 AM) comp.soft-sys.math.mathematicaAnother question, along the same lines. Some of the solutions Mathematica gives me include compound fractions of the form ((A/B)-C)/ D. Again it seems to me most authors would rewrite this as a simpler fract...paulvonhippel (114) TransformedDistribution -- odd problem 6 27 (7/24/2011 7:22:36 AM) comp.soft-sys.math.mathematicaI'm having a very strange problem with TransformedDistribution, where I can calculate the mean of an F distribution but I cannot calculate the mean of a constant multiplied by an F distribution. That is, if I...paulvonhippel (114) Fast simple regression 17 22 (10/10/2011 9:32:37 PM) comp.soft-sys.sasWhat is the fastest way in SAS to carry out a simple regression (one X variable, one Y variable)? All I want is the slope, intercept, df, and MSE. I don't need standard errors, t statistics, or p values. And I ...paulvonhippel (114) Export list to Excel without brackets 5 36 (10/18/2011 11:44:58 AM) comp.soft-sys.math.mathematicaLike a previous poster, I would like to export a list to Excel. Here is my list: {{{1.27,1.12,1.00,0.90,0.83},{0.27,0.12,0.00,-0.10,-0.17}, {0.66,0.56,0.49,0.43,0.38},{0.72,0.57,0.49,0.44,0.42}}, {{1.09,1.0...paulvonhippel (114) random number generator gives same result repeatedly 2 24 (12/12/2011 9:27:45 PM) comp.soft-sys.sasI'm imputing missing values using code that reads, in part, as follows: do D=1 to 3; if missing (x1) then x1 = intercept + slope * x2 + RMSE * rannor(0); output; end; I expect to see three different imp...paulvonhippel (114) Alternative to "by" statement 7 22 (12/13/2011 9:27:41 PM) comp.soft-sys.sasI want to do apply an algorithm to my data. If the algorithm were implemented in a PROC, I would do this. PROC DO_SOMETHING DATA=my_data; RUN; In fact, the algorithm is implemented in a macro, so I do this:...paulvonhippel (114) PROC IML: extra eigevalues = 0 1 29 (3/24/2012 7:51:10 PM) comp.soft-sys.sasHere's some behavior that I don't understand from PROC IML. In the following output, there's an extra column of zeroes at the end. They appear to be part of eigval_g. Why? proc iml; w = {0.0106126 -0.004901, ...paulvonhippel (114) Extrapolation using TRANSREG 1 35 (4/29/2012 1:11:33 AM) comp.soft-sys.sasUsing the MSPLINE transformation in PROC TRANSREG, I wish to obtain predict= ed Y values for X values that are not observed in the data. I can do this f= or X values that are within the range of the observed X ...paulvonhippel (114) Linear extrapolation 3 25 (5/2/2012 3:04:40 AM) comp.soft-sys.sasI want to add rows to the bottom of a dataset, where each row differs by a constant from the row before. The constant is the difference between the last two rows before I start adding. For example, if the input...paulvonhippel (114)