Dear Dr Kerenza Hood,
I guess you have already received many replies. Excess zeros means
inflated zeros and use is made of the Zero-inflated Poisson(ZIP)
regression. The following reference might be of help:
Lambert,D.(1992). Zero-inflated Poisson Regression with application to
defects in Manufacturing. Technometrics, vol.34, pp 1-14.
Sincerely yours,
June E.Simakani
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MSc,GradDip(Stats),PGDTE,CDipAF,CStat
Department of Mathematical Statistics
Nelson Mandela Metropolitan University
Vista Campus ,P.O.Box 77000
Port Elizabeth 6031
South Africa
Tel.no: +27(41)408 3234
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