This is the description of my study. We have 4 fungicides ( 1 (control treatment, fungicide only), 2 (fungicide with excipient A), 3 (fungicide with excipient B), 4 (fungicide with excipient C) that we used on cereals. We have determined the residues of the fungicides in the course of 6 weeks (week 1,2,3,4,5,6).
Research question:
Is the degradation of the fungicide with excipient different than the degradation of the control treatment?
Should i use a two way anova test? should i take the time in account?
If all assumptions are met, yes you can use a 2-way split plot ANOVA with one within and one between factor. As post hoc test you could use contrasts instead of pairwise comparisons (e.g. if you want to compare all treatments together against the control condition).
But one thing you should take care of: is you dependent variable suiteable for the genereal linear model, which assumes to have normally distributed residuals? It may be expected that this wont work properly if your dependent variable are count data for example.
My dear
You can use three methods for this study:
1- split plot analysis in time when time factore as sublpot
2-Multivariate analysis for p times(6)
3- Repeated measure analysis (I am have atrical in my researchagte you can Donwload it)
Regards
If you want to compare week and fungicides together, yes, use two-way ANOVA. Of course, its interpretation becomes a bit complicated.
The best software to do ANOVA is GraphPad Prism. Be sure to use it. There is good charts.
It looks it is the case of one-way ANOVA. You have to test different type of fungicide - so, it is one-way.
For two-way, you should add some extra factor, such as season, or humidity, or so on. In this later case you will test the fungicide (factor 1) as depending on season (factor 2).
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