# glm

1. ### Plotting the results of GLM in R

I have this data plotted as a scatter plot in Excel I had done a regression in Excel, and the p value was 2.14E-05 while the R- value was 0.32. I was told the R value was too low compared to the significance of the p value, and was told to control for the dispersion of the data by running it...
2. ### Transform data for factorial two-way ANOVA/General Linear Model??

Hi, I'm not very statistically minded but I would really appreciate some guidance. I am needing to do several stat tests for my MSc dissertation. I have one dependent variable (species count) and one independent variable (year), but two species. I have constructed a basic count against year...
3. ### Repeated measures design - correct analyses and GLM assumptions

Hi all, I have collected data for a study but I am not sure now if I am carrying out the correct analyses. I have tried for the last few days to figure out whether my analyses are correct, but I keep getting a lingering doubt that they are not and so I thought I will ask this question because...
4. ### Indices with data bound between -1 and +1

Hi all, I would really appreciate some advice on how to deal with my data. I would like to compare data calculated from an index which is bounded by -1 and +1. I was surprised to see that previously published use of this index has been analysed using standard ANOVA, because I was led to...
5. ### Help with glm--- Simple Logistic Regression

Hi All! Thanks for reading. I wanted to compare month of sample collection (April, May, June, and July) to presence/absence data (coded in binary dummy variables). I tried to run a Simple logistic regression, but realized that the output table with p values, etc all report for may, June, and...
6. ### GLM in SPSS

Hi, I am trying to do something quite simple but I am so confused about how to enter my data into SPSS and which test to use. I have four subjects whose performance is measured at ten time points and I want to know if their scores are changing. Normally I would enter my data with one subject...

8. ### Help with model Matrix GLM

Hey guys been browsing the forums for a while, and usually find what I need! This is a tad more specific though so Ive made an account!! I've been puzzled by the form of the model for a while.. The model states that the response depends upon y~smoke + drink +smoke:drink +age:smoke. The model...
9. ### Binomial response variable with 3 continuous and 1 categorical predictor. Best test?

Hello I have a binomial response variable. Predictors are composed of 3 continuous variables (the results of a Principle Components Analysis of habitat structure variables) and 1 categorical variable (habitat type e.g. grazed or ungrazed). I want to test whether the 3 habitat variables have...
10. ### Type I and Type II SS for ANOVA, non-statistician

Good Afternoon (non-statistician here), I have to automate a GLM within an Excel sheet that will be analyzing some toxicity data, resulted from scoring cell aberrations. And, I'm using MiniTab to validate the estimates. MiniTab is using Type I (sequential) SS and Type II (adjusted) SS within...
11. ### How to model weighted average ratios in the [0,1] interval

Maarten Buis on this forum provided great insight on how to model percentages in the [0,1] interval (http://www.talkstats.com/showthread.php/52986-Modelling-percentages-in-the-closed-interval-0-1). I now have a similar but somewhat different problem, in that I'd need to model weighted average...
12. ### Maximum likelihood estimation and GLMs - can you help me refresh my rusty memory?

Hi all, I was wondering if you can help me refresh my rusty memory on maximum likelihood estimation. I think I remember the basic concept from my university courses in a previous life. Banal example: we want to fit a normal distribution to the observations 3,4,5, then N(4,1) is the best...
13. ### Data analysis with a GEE, is my method valid?

Hi everyone, I’ve been doing some statistical analyses in R on some data. It’s for use in a manuscript I’m hoping to get published in a biological journal. Unfortunately, the tests I ended up having to run are kind of at the limit of my understanding, so I was hoping that I could run through...
14. ### GLM with non-parametric post hoc testing?

Hi guys, I have a question regarding the appropriate use of comparisons for independent samples (3 factor levels), please. Overall sample size is N=546, subsamples: 218 or 228 or 100), convenience sampling, stratified. I use ANOVA with post hoc Tukey, if Levene indicates variance...
15. ### Comparing count data and cultivars in R

Hi, I'm trying to analyse an experiment with this setup: A plant species with 16 different cultivars of 4-5 plants per cultivar (completely randomised within greenhouse, no blocks) An insect species that was allowed to spread freely for 4 days on the plants. The insect number per plant was...
16. ### How to analyse deviance (GLM in R)

Hi! This might be quite basic, but how do I analyse the fit of my GLM from the deviance? In the summary of my model, I get a deviance of 140.1 (df.resid = 52). Can I tell from these numbers, if the fit is acceptable? Thanks in advance for any replies!:tup:
17. ### Fit of generalized linear model (Poisson distribution)

Hi guys Can anyone tell us how to evaluate the fit of our generalized linear model with a poisson distribution? We can't really tell if the model is a good fit or not. Do you use the deviance to answer this question? If so, what does it tell us in the following example? Thank you in advance...
18. ### Which statistical analyses do I need to use?

Hello everyone! :wave: I'm having some trouble resolving two assignments with SPSS. First one is that I need to analyse if there's a difference between poor and rich European countries (using a GDP per capita index variable) and link it with thinking that the environment is the most important...
19. ### Constant negative fitted values...am I missing something?

Hello all, I'm attempting to fit a model where y variable is a variety of \$/ha/year figures (all positive) ranging between 0.01 and 2520. The output of this should always have positive fitted values (none of these values should ever be below 0), and yet I get constant negative fitted values...
20. ### In a negative binomial GLM or GLMM what does theta stand for?

When using a GLM or GLMM with a negative binomial distribution in R it is usually necessary to set the value of theta in the model. But what does theta actually stand for? And how do I caluclate it? I have been able to get around this for now by setting my models to calculate theta for me...