solved

  1. S

    PRIMER- MDS-shows identical biological community samples equally different, WHY?

    Hi, I have a large data set of marine intertidal organism abundance (measured as percent cover. I also have environmental data of substrate type, and beach exposure to wind/waves. The research question is “Do unconsolidated beaches (eg. sand or gravel, not bedrock) have different communities...
  2. K

    Post-hoc Tukey with Mixed rANOVA in SAS

    Hi all, I am working on the analyses for my dissertation. My study uses a split-block design, and I have performed a Mixed rANOVA (one between subjects with three levels -- group, and one within subjects with three levels -- time) using PROC GLM, and I had a statistically significant...
  3. Z

    Need help - upper bound estimation

    Hello! I am making my college conclusion project, and my deadline is dreadfully close! I need to find out a way to estimate a variable, and I have been researching the internet for a few hours now without success. I have no other option other than resorting to asking for help on this forum...
  4. P

    Comparing signal amplitude across multiple timepoints– what method should I use?

    Hi there, I am working on a research project looking at the effect of mood on brain response during visual perception. 20 volunteers participated in the study, 10 in the ‘happy’ group and 10 in the ‘sad’ group. Electrical current was recorded in a specific brain region while the participants...
  5. ledzep

    Grab first sequence for each unique values in a column

    Dear R Users, I want to keep only the very first sequence for a given number. Example Data d.f<-data.frame(var1=c(5,5,5,1,1,2,2,5,5,3,1,1,1)) >d.f var1 1 5 2 5 3 5 4 1 5 1 6 2 7 2 8 5 9 5 10 3 11 1 12 1 13 1 # Unique Values > unique(d.f)...
  6. ledzep

    Question on strptime with peeling out hours

    Dear R users, I am trying to peel out information on hours from a column which contains information on date and hours. An example # data x<-dput(structure(list(date = structure(c(4L, 3L, 1L, 5L, 2L), .Label = c("01/14/92 01:03:30", "02/01/92 16:56:26", "02/27/92 22:29:56"...
  7. J

    hypergeometric? mean and variance

    [SOLVED] hypergeometric? mean and variance Consider a group of T persons and let a_1, \ \ldots \ , a_T denote the heights of these T persons. Suppose that n persons are selected from this group at random without replacement, and let X denote the sum of the heights of these n...
  8. T

    Count frequency

    Hi. Let say i have a data xdata=c(0,1,2,0,0,4). So, i want to obtain the frequency of this data including the "missing" possible value (which in this case is 3). Basically, i want my output looks like this: x 0 1 2 3 4 freq 3 1 1 0 1 My “half-done” R code with error: >...
  9. TheEcologist

    [Solved] [R] Convert character to command

    He guys, I've been wondering if this is in someway possible in R. Maybe someone here knows. Lets say you have a set of R-commands saved as characters, how do you convert these to commands? # lets say we have the following a="rep(c("A", "B"),each=2)" # its classified as a character class(a)...
  10. B

    [Solved] Problem with regards to Poisson! Need some help.

    Provided information; No. of particles in sample / No. of samples 0 / 32 1 / 47 2 / 37 3 / 18 4 / 4 5 / 2 >=6 / 0 Question: If a sample taken at a later date has 7 particles in a standard sample, does it seem that the quality is deteriorating? (Explain your answer, and how you...
  11. G

    [Solved] Significance in R

    Ok, this is quite hard to explain, but I'm at a complete loss what to do. I'm a relative newcomer to R and although I can completely admire how powerful it is, I'm not too good at actually using it.... Basically, I have some very contrived data that I need to analyse (it wasn't me who chose...
  12. P

    comparing the DEGREE of difference between data sets

    Hi all, I'm wondering if there is a way to assess the degree of difference between data sets. For instance, say I have 4 groups of proportions (or 4 data sets that these proportions were generated from), A, B, C, and D. Is there a way to determine which group out of A, B, and C is most alike...
  13. TheEcologist

    Solved and Workaround tags

    Hi guys, How useful would you guys think it is if the mods started adding [Solved] or equivalent tags to problems that have been answered? This practice may even encourage help-seekers to do the same. Its should make it easier for people to find useful topics when searching the forum. Tell...
  14. S

    [Solved] Use mean or not?

    Hi everbody, Here's probably a quite simple question but I just want to be sure before doing tests on it. I'm not sure if I have to take the means of my data or not, here's a short description of my experiment: I have 18 single blocks where I measured, at each block on two areas. So...
  15. E

    [Solved] Script writing for PCA in R

    Hi, I am new to R and am trying to perform a principal components analysis on my data. I have 5 columns, these are: year, A, B, C, D. I want to combine measures A,B,C and D each year using a PCA. I can import my .csv file, but I was wondering how to write the script for this analysis...
  16. A

    [Solved] Dichotomizing variables

    Can anyone tell me how to dichotomize a variable into thirds? I have two likert-scale questionnaires, and I want to see if there is a significant difference in the scores on scale B, depending on the score in scale A. I was going to divide the results of scale A into high, medium, and low...
  17. R

    Ancova help

    Hi, This is my first time posting here, so please forgive me if I'm not accurate enough. I've been doing an ancova in R. This is what I have been doing so far: rpdmod1x<-lm(rpd2~1) rpdmod2x<-lm(rpd2~vh2) rpdmod3x<-lm(rpd2~ex2+vh2) rpdmod4x<-lm(rpd2~ex2*vh2)...