random factor

  1. A

    Need formula to determine size of group

    I have 16 questions in an exam that chooses 3 questions at random each time the exam is presented. How many times must the exam be taken in order to compile 10 responses for each question? Tried to search for an answer but kept getting an error.
  2. K

    Confidence intervals from glmer models

    Hi! When reading this, please keep in mind I'm pretty bad with statistics so please bear with me. So, I'm trying to analyse data from an ecotoxicological experiment. I have fish that were exposed to a substance during development and want to look at behavioural effects in the adult fish. I have...
  3. L

    Aligned rank transform with random factor

    In a book, I've found SPSS syntax for performing an aligned rank transformation in a two way ANOVA. The procedure is: - save residuals by performing a standard ANOVA - use Aggregate to determine effects for group means (mij for interaction, ai as first factor, bj for second factor) -...
  4. A

    No Value for Wald chi2 or prob with random effect in negative binomial regression

    Hello all! So I'm doing a negative binomial regression, for my DV (timecz) and the interaction of two IVs (predation and age). I added in a random factor, spkr, and I get no values for the Wald chi2 or prob. 'spkr' has values 1, 2, 3, 4 so it is a categorical variable, and every one of my data...