 
Greetings R Help Group,
 
How does one effect a multiphasic logistic growth model with 4 phases (e.g. Koops 1986; Weigel, Craig, Bidwell and Bates 1992; Grossman and Koops 2003) with R.
 
Before writing to the group, the R help archives were searched, the web was searched with Google, Venables and Ripley 2002 was consulted, Pinheiro and Bates 2000 was consulted, Bates and Watts 2007 was bought and consulted, ETC. but to no avail.
 
I have not written to any other group with respect to this problem.
 
The following data are offered as an example of the type of problem I am dealing with and are average daily goat milk production in ml. for 14 weeks. NoC is the goat number. PL1 is the production during the first week; PL2 is the production during the second week, etc.  
 
 NoC  PL1  PL2  PL3  PL4  PL5  PL6  PL7  PL8  PL9 PL10 PL11 PL12 PL13 PL14
  52  490  950  800  900  850  850  750  610  640  900  980  890  890  910
  48  970 1020  980  740 1050  970  850  790  900  920 1120 1120 1030 1300
  54 1450 1420 1430 1120 1330 1230 1030 1170 1350 1530 1490 1500 1310  910
  60  620 1250 1100 1150  780  930  990  940  760  730  790 1050  840  850
  58 1370 1350 1200 1300 1350 1310 1070  910 1010 1300 1110 1070  990  660
  42 1200  920 1150  850  720  630  630  710  850  810  930  980  820 1570
  44 1200 1560 1650 1600 1450 1600 1160 1010 1440 1450 1530 1500 1550  850
  47 1000 1100 1000  870  760  900  820  865  910  820  930  900 1130 1070
  50 1300 1150 1200 1030 1070  970  860  900  950 1190 1250 1130  800 1400
  56  950 1250 1200 1280 1220 1155  840 1016 1370 1220 1570 1520 1500 1150
   1  870 1250 1160 1270 1200 1410 1110 1008  970 1130 1490 1330 1320  820
   3 1000 1100 1200 1120 1250  980  750  890 1050 1160 1340 1210 1150  760
   4  551  760  550  580  540  620  550  520  470  720  680  790  750 1230
   5  810 1100  820  950  930  830  850  650  810 1070 1120 1300 1040 1320
   6  800 1000  620  850  750  670  660  620  600  610  760  900  758 1070
   7  720  830 1120 1050  820  820  850  810  800  750  780  940 1050 1310
   8  950 1550 1560 1500 1230 1330 1150 1005 1020 1200 1440 1400 1290 1080
  10  660  850 1100  980 1070 1100  870  790  880  950 1000 1210 1050 1220
 
It seems to me that it should be possible to effect the modeling process with nlme. Any suggestions and or recommendations would be greatly appreciated.
 
Peter B.
 

 
Douglas M. Bates and Donald G. Watts. 2007. Nonlinear Regression Analysis and Its Applications. Wiley Series in Probability and Statistics. John Wiley & Sons, Inc., New York, NY, USA.
 
M. Grossman and W.J. Koops. 2003. Modeling Extended Lactation Curves of Dairy Cattle: A Biological Basis for the Multiphasic Approach. J. Dairy Sci. 86:988-998.
 
W. J. Koops. 1986. Multiphasic Growth Curve Analysis. Growth 50:169-177.
 
Jose C. Pinheiro and Douglas M. Bates 2000. Mixed-Effects Models in S and S-Plus. Statistics and Computing. Springer-Verlag New York, New York, NY, USA.
 
W. H. Venables and B. D. Ripley. 2002. Modern Applied Statistics with S. Fourth edition. Statistics and Computing. Springer-Verlag New York, Inc., New York, NY, USA.
 
K. A. Weigel, B. A. Craig, T. R. Bidwell and D. M. Bates. 1992. Comparison of Alternative Diphasic Lactation Curve Models under Bovine Somatotropin Administration. J. Dairy Sci. 75:580-589.
 
 
 
 
 
 
 Peter B. Mandeville cel:      444 860 3204 tel:  52 444 826 2346-49 ext 532 fax: 52 444 826 2352 P.D. Favor de confirmar la llegada de este correo. Gracias.
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