1. M

    Dealing with temporal autocorrelation

    Hi, assume we have a measured value for each year from 1990-210, and we want to estimate a linear trend. Now there is a problem of autocorrelation, i.e., the measured values do not scatter randomly around the fittet line but rather resemble a "smooth function" wriggeling around the linear fit...
  2. P

    Brownian motion around a sinusoid.

    I wish to model arrivals of people into a healthcare queue. The methods I have studied involve assuming that the arrival rate is constant - but the data clearly show this is not true, it shows a sinusoidal pattern. I was thinking of fitting a sinusoid to the data (using least squares), then...
  3. R

    Non-linear modelling with several variables including a categorical variable

    Hello everyone, I am trying to model some data regarding a predator prey interaction experiment (n=26) in R. Predation rate is my response variable and I have 4 explanatory variables: predator density (1,2,3,4 5), predator size, prey density (5,10,15,20,25,30) and prey type (3 categories). I...
  4. C

    Gam calculations on groups of data and modeling on an xyplot

    Hi there, I am hoping someone will be able to help me with a problem I have been having. I haven’t used R much so I am sorry if it is really obvious. I have a dataset that contains population values for certain years. In the dataset there are different ID groups with a number of years...
  5. S

    GAM with Gamma distribution-Default Inverse Link or Log-Link?

    solved. thank you!
  6. C

    Input data for a GAM

    Hi there, I am trying to use a GAM (with the mgcv package) to look at species abundance. I have created a data frame for input into the model but the model will not pick up the column headers when I create my function. This also spawns the error message 'object is not a matrix'. I have also...
  7. S

    obtaining numeric correlations within scatterplot matrix(pairs)?

    Hi all, I have created scatterplot matrixes for my data but cannot for the life of me figure out how to obtain and then insert the correlations in the matrix. I had read posts online but I am generating errors. My pairs formula is pairs(~glass_sponge+Depth+S+M+Sm+P,data=Gs) I looked at...