  I review galaxy number count models and present ncmod, an extendable and
general purpose model for comparing and interpreting the results of field
galaxy survey data. I develop techniques and software for converting the
results of a survey done in one filter into another filter, for direct
comparison with other surveys. Comparison of the data from surveys which differ
greatly in wavelength coverage or sensitivity is of necessity model-dependent,
but comparison between similar surveys can be done in a relatively
model-independent way. I extrapolate existing number counts into the
ultraviolet and thermal infrared. The model is used to predict the results of
future space missions, including STIS and NICMOS on HST, ISO, SIRTF and NGST.
