Hello, I am struggling to figure out how to analyse a dataset I have inherited (please note this was conducted some time ago, so the data is as it is, and I know it isn't perfect!). A brief description of the experiment follows: Pots of grass were grown in 1l pots of standad potting medium for 1 month with a regular light and watering regime. At this point they were randomly given 1l of one of 4 different pesticides at one of 4 different concentrations (100%, 75%, 50% or 25% in water). There were 20 pots of grass for each pesticide/concentration giving 320 pots. There were no control (untreated) pots. The response was measured after 1 week and recorded as either: B1 - grass dead B2 - grass affected but not dead B3 - no visible effect I could analyse this as lethal effect vs non-lethal effect (B1 vs B2+B3) or some effect vs no effect (B1+B2 vs B3) binomial model, but I can't see how to do it with three levels. Any pointing in the right direction greatly appreciated! Thanks Matt
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