This data set gives the root counts for propagated columnar apple shootrs, in which the shoots were cultured on different concentrations of the cytokinin BAP, in growth cabinets with an 8 or 16 hour photoperiod. The appleshoots data has 270 observations.
data(appleshoots)
A data frame with 270 observations on 4 variables.
number of roots per shoot
number of shoots per treatment combination
photoperiod, 8 or 16
BAP concentration, numeric
The agridat package
Wright, K. (2021). agridat: Agricultural Datasets. R package version 1.18. https://CRAN.R-project.org/package=agridat
Ridout, M. S., Hinde, J. P., and Demetrio, C. G. B. (1998). Models for Count Data with Many Zeros. Proceedings of the 19th International Biometric Conference, 179-192.
SAS. Fitting Zero-Inflated Count Data Models by Using PROC GENMOD. support.sas.com/rnd/app/examples/stat/GENMODZIP/roots.pdf
## For examples see example(glm.izip)