[R] simple on point bisserial correlation
Dear developers of R-project, I have such data height of male persons 181, 178, 182, 160, 187, 193, 184, 184, 175, 178, 184, 184, 174, 185, 175 height of female persons 164, 165, 160, 174, 167, 161, 164, 165, 169, 175, 165, 155, 172, 164, 172, 166, 160, 159, 158, 173 I want to determine if height is dependent on gender, and I need to find, as I understand, point biserial correlation. I had tried to use package ltm, and obtained coefficient which is about 0.74. I also had tried to calculate it manually (with some MS Excel help for simple calculations), using equation given in Internet (e.g., in Wikipedia; this equation is also given in some copy-books) and obtained coefficient is about 0.77. ltm provides somewhat other equation with pi-numbers. So, the questions are following: 1). Do exist packages in R-project, except of polycor and ltm, which provide calculation of point biserial correlation? 1a). Why ltm use non-traditional equation for bisserial coefficient? Which is significance of this difference? 2). Can I also calculate significance of the biserial correlation coefficient (p ???; using, probably, t-test) by means of R-project? Thank You for advance. With regard, Dmitry Gospodaryov. __ 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.
[R] histogram
Dear R developers,How I can build a histogram from matrix: 0 0.5 1 0.25 34 43 65 1 23 35 54 4 22 29 42 10 21 22 29 20 15 17 20 (first string is represented names of columns, first column is represented names of rows) where names of columns should be x-axis labels; respectively to this, I want to have three groups of bars (5 bars in each group)? Y values should be represented by values given in the core of matrix. Names of the rows should be in a legend, and should represent the each of 5 bars (in group) name. I would also try to build filled contour, however, i can't ask the program to consider column and rownames like true values, not only like labels. So, column names should be the y-values, while row names should be the x-values. Values placed in the core of matrix should be z-values. With regard, Dmitry. __ 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.
[R] response surface designs
How I can obtain graphics for response surface design, basing on data: x: 0.25, 1, 4, 10, 20. y: 0, 0.5, 1 z1 (for y = 0): 45, 35, 25, 15, 10. z2 (for y = 0.5): 50, 45, 36, 21, 17. z3 (for y = 1): 37, 34, 22, 17, 11? z-values should be scaled in colour (e. g. from red to blue). I consider to use packages rsm and graphics (with grDevices). I suggest to use Box-Behnken design in rsm and filled.contour in graphics. However, I do not know how I can combain these two opportunities. I am not familiar in response surface analysis, and able to be wrong in the selection of the model. Thank you for any reply. With regard, Dmitry. __ 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.
[R] some simple questions regarding survival analysis
I have two types of survival data for Drosophila cohort. For example: uncensored age - c (0, 2, 4, 6, 8, 10) alive1 - c(10, 9, 6, 3, 1, 0) alive 2 - c(10, 9, 4, 1, 1, 0) and censored age - c(0, 2, 4, 6, 8, 10) alive1 - c(10, 8, 3, 1, 1, 0) escaped1 - c(0, 1, 1, 0, 0, 0) alive2 - c(10, 7, 2, 1, 1, 0) escaped2 - c(0, 1, 2, 0, 0, 0) 1) What statistical tests is the most apropriate for the correct comparison of uncensored data (alive1 and 2) and censored ones? 2) What package and function I can use in R for the above mentioned comparison? 3) Should I rearrange the data in the example tables for the correct calculations using R functions? With regard, Dmitry. __ 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.
[R] Tool for solving equations
Does exist any tool in R to solve equations, especially complex exponential equations? For example: y = 100*exp(b*(1-exp(c*x))/c) If it is so, then what is the package i have to use and what is algorythm for this solving? Thank you for advance. With regard, Dmitry. __ 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.
[R] Difficulties with the simpest table
I have the data arranged in table (in Excel, or Notepad): x y 0 100 2 100 4 80 6 40 8 0 I need to transfer these data in R file and then going to operate with x and y as with variables. I should note, that I have 2.8.1 version. Thank you for advance. With regard, Dmitry. __ 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.
[R] curve fitting
I have the data: for x: 2, 8, 14, 20, 26, 32, 38, 44, 50, 56, 62, 68, 74, for y: 100, 99, 99, 98, 97, 94, 82, 66, 48, 38, 22, 10, 1. y depends on x by equation: y = 100*exp(b*(1-exp(c*x))/c), where b and c are coefficients. I need to find coefficients in this equation for given data. How can I do that by means of R? Thank you for advance. With regard, Dmitry. __ 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.
