  More than about 50% stars are in binaries, but most stellar population
studies take single star stellar population (ssSSP) models, which do not take
binary interactions into account. In fact, the integrated peculiarities of
ssSSPs are various from those of stellar populations with binary interactions
(bsSSPs). Therefore, it is necessary to investigate the effects of binary
interactions on the Lick indices and colours of populations detailedly. We show
some formulae for calculating the difference between the Lick indices and
colours of bsSSPs, and those of ssSSPs. Twenty-five Lick indices and 12 colours
are studied in the work. The results can be conveniently used for calculating
the effects of binary interactions on stellar population studies and for adding
the effects of binary interactions into present ssSSP models. The electrical
data and fortran procedures of the paper can be obtained on request to the
authors.
