IGF data frame has 237 rows and 3 columns.
This data frame contains the following columns:
an ordered factor giving the radioactive tracer lot.
a numeric vector giving the age (in days) of the radioactive tracer.
a numeric vector giving the estimated concentration of IGF-I protein (ng/ml)
Davidian and Giltinan (1995) describe data obtained during quality control radioimmunoassays for ten different lots of radioactive tracer used to calibrate the Insulin-like Growth Factor (IGF-I) protein concentration measurements.
Davidian, M. and Giltinan, D. M. (1995), Nonlinear Models for Repeated Measurement Data, Chapman and Hall, London.
Pinheiro, J. C. and Bates, D. M. (2000), Mixed-Effects Models in S and S-PLUS, Springer, New York. (Appendix A.11)