You're right. I think I was assuming that the mean response would be based off of my observed values rather than my predicted values (despite saving my "Prediction foruma". Doh). In hindsight, I see why I'm getting constant values when my response is the intercept. The vast majority of my work up until this point has been dealing with normal distributions and I guess I was trying to use the predicted values to fit a line to my observed values as best I could (similar to a linear regression). I'm sure I'm still miscontruing a lot of this but I'm beginning to see why I have problems. My response is indeed total count (of eggs). While I had originally used a Poisson model before, people had recommended using a negative binomial distribution since it appears that I'm dealing with overdispersion. I wouldn't necessarily say I have a definition of success or failure in my model. Unless the presence of eggs was considered a "success" although that's ultimately not really what I'm interested in. So, I'm sure you're right that I should likely be using a Poisson distribution. Is it possible to apply a overdispersion parameter to a Poisson model in JMP? Would you mind clarifying what you mean by "area of opportunity". A block in my situation has a single replicate of all of my treatments within it (randomized) in an attempt to deal with spatial heterogeneity. Unfortunately, I only had two blocks in my model (was limited by space and funding). Plots A through E in my panel represent the 5 different metrics that I'm looking at: total egg count (per reef), female per capita, male per capita, egg production per nest, and egg production per clutch. Essentially they're all different ways of looking at reproductive output in my species. Plots with a trend line are significant. Plots A, D, and E all had a signficant interaction (sex ratio * block; proportion male and sex ratio are used interchangeably in my study) but nothing else after selection. Just sex ratio was significant for Plot C. The scale of the response differs but in all 5 plots it's egg count. Really, really appreciate all of your input so far Mark. Your replies have cleared up a lot of things for me. Thank you!
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