1. O

    How to predict a model with multiple factors?

    Hi, My question is probably trivial but I cannot figure it out... I'm doing a glm with multiple continuous and categorical predictors. In R, the summary() gives the estimates of factors' levels as contrast to the intercept (right?). So, If I'm modelling, let's say, diet and sociality as...
  2. Y

    Logistic regression or GLM?

    Hi everyone: I have a question about using logistic regression or GLM with only categorical variables as independent variables. The dependent variable y is shown as binary coded data where 1=males and 0=females. Each corresponding to an excrement. The independent variables are as follows...
  3. jpkelley

    Variation in inflection point for modeled logistic curve

    Hey all. Question category: R and regression; Posted in R forum since R code. Question: How best to quantify variation in an inflection point for a logistic curve? Background of problem: Birdies begin their birdie lives contained in eggs. Then, they hatch and continue their lives...
  4. L

    Regression Analysis - Transformations and Non-Normality

    Hello, I am fairly new to regression analysis and have a few questions.. I have a fairly large dataset containing information about 144 municipalities in a country. I am trying to create a model that uses a number of independent variables (urban ratio, literacy rate etc.) to model the...
  5. K

    GLM: possible to constrain 1 beta weight?

    Hi, I am interested in comparing two design matrices in which the parameter values of interest are perfectly negatively correlated. Of course, via traditional GLM, these design matrices yield identical residuals, as the sign of the beta corresponding to the parameter of interest flips between...
  6. A

    How best to account for seasonality when analysing bird monitoring data

    Hello All, I have some monitoring data from seabird surveys carried out in an offshore construction site. Surveys were undertaken before, during and after construction and I am trying to evaluate whether there were significant effects on the observed seabird densities as a result of...
  7. T

    Repeated Measures GLM or Logistic Regression?

    I have a question that I'm hoping somebody here can help me with. I am a student working on my psychology thesis and am having some difficulty analyzing my data. I gave 300+ participants a questionnaire. They all answered a personality measure (continuous scale) and all gave their gender. I...
  8. E

    [Anova using R] Likely need help setting up a multi way ANOVA, open to other options

    I am analyzing the data from an MRI experiment where we tested a new contrast agent against two control agents in mice with tumors. The experiment There were three treatments. Each treatment was given to three mice. Each mouse was imaged at 16 timepoints. I am analyzing three image slices...
  9. K

    Detecting outlier sample sites

    I have binomial frequency data for an allele associated with populations living in mountainous. These mountains run north to south where sites are nearly fixed for this allele and lowland sites to the east that lack the allele. At the south end of the mountains is a hybrid zone. Despite the...
  10. A

    Interactive terms

    Afternoon all, I've been running some GLMs using a stepwise backwards deletion routine (main effects, 2 way, 3 way), deleting the least significant terms between each repeat. I've found some significant interactive terms and just wanted to check that my interpretation of what these mean is...
  11. A

    GLM output

    I am conducting a series of GLMs in order to find the minimum adequate model, the largest model in which all factors are significant. In some of my models all factors are significant, except for the intercept... what does this mean?? thanks andy
  12. A

    Bonferroni correction in GLMs

    I'm running a series of General Linear Models, attempting to explain factor x with 6 other factors; individually, all 2-way and all 3-way. Due to the large number of significances which I am trying to find is it neccessary to apply a Bonferroni correction to effectively decrease the p-value...
  13. Z

    Very long post - need help thanks

    Dear All, I am writing to you because I have got a lot of troubles with some concepts regarding Generalised Linear Models. I need to understand it by the January 2012. I hope it is possible. I am currently getting through one of the books regarding generalised linear models in a pretty much...
  14. D

    Quantitative analysis help please!

    - edit - Thanks anyway!
  15. N

    GLMs in Life Assurance - using an Expected "framework"

    I work in Life Assurance and the GLM concept is fairly new to us. To date, we have analysed our mortality experience in the following way - Define an Expected mortality table (this might be a standard published table - or an internal table derived from a prior analysis) - This table...
  16. A

    Co-efficient interpretation in Gamma Regression Model

    Hi Guys, I am trying to fit a gamma regression model using a log link model. Now, I get a negative co-efficient for one of my IVs. What is the best way to interpret this? Should I exponentiate this co-efficient? What does this mean in that case? Thanks for the help.
  17. M

    GLM for proportional data

    Hi, I'm hoping someone can help me sort out question about how the proportion comparisons in GLM works in R. I'm trying to compare hatch success among years (and later, sites). I've used a GLM to compare among years by making a txt file where the success column contains the number of chicks...
  18. M

    Confidence intervals for a binomial distribution

    Hi everyone, In my thesis data set, I'm trying to sort out which years were poor and which were good based on an assortment of breeding bird metrics. The one I'm currently looking at is clutch size, where I've converted 1 and 2 egg clutches (this species never lays more) to a binomial...
  19. M

    GzLM for counts or ?

    Hi everyone, I'm trying to figure out how to run an appropriate comparison for clutch sizes of birds. Ultimately, I want to compare clutch size of the same species between 2 sites with 2 levels (good, poor). First I need to sort out if there were differences among years in each site to be able...
  20. P

    Transforming z to t values (GLM, different error distributions)

    Hi, I am comparing behavioural data collected at two populations. Generalised linear models were used with a behavioural trait as a response variable. The problem is that due to the error distributions, different families were specified for each dataset: Gaussian and Binomial family...