Felipe Carrillo <[EMAIL PROTECTED]> wrote in news:[EMAIL PROTECTED]:
> Dear All: > Using the Excel formula below I am able to estimate > daily variance(Daily VarPD)for PD,but I can't figure > out how to estimate the Weekly variance for PD. Any > hints? > > Daily VarPD = (PD * (1 - TD))/TD + VarTD * > ((PD*(1-TD)+ PD^2*TD))/TD^3 > > > WK TD VARTD PD Daily VarPD > 28 0.014735 0.0000449 0 0 > 28 0.012421 0.0000449 0 0 > 28 0.014396 0.0000449 71 7005 > 28 0.014898 0.0000449 132 14016 > 28 0.013512 0.0000449 223 32506 > 28 0.013886 0.0000449 224 31287 > 28 0.013778 0.0000449 218 30528 > 29 0.013274 0.0000449 228 34505 > 29 0.013072 0.0000449 224 34531 > 29 0.012518 0.0000449 488 117720 > 29 0.013264 0.0000449 525 119323 > 29 0.013233 0.0000449 80 9134 > 29 0.010194 0.0000449 417 133067 > 29 0.012567 0.0000449 82 10184 > 30 0.014695 0.0000449 413 68893 > 30 0.010634 0.0000449 373 103688 > 30 0.013934 0.0000449 914 272719 > 30 0.014107 0.0000449 213 28473 > 30 0.014339 0.0000449 651 147016 > 30 0.014375 0.0000449 521 102429 > 30 0.016373 0.0000449 979 229104 I am going to assume on the basis of your earlier posts that you have gotten this into a dataframe. You should know, since Prof Ripley told you so six months ago, that variable names cannot have spaces. The formula you offer makes no sense to me, and I could not see what bearing it has on calculating a variance of a week's worth of PD values. In the future, you should offer code to create a minimal dataset. Assuming your dataframe is fishwk, here is a method to get the variances of PD by week: by(data=fishwk, INDICES=fishwk$WK, function(x) var(x$PD)) -- David Winsemius ______________________________________________ R-help@r-project.org mailing list 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.
