Interpretation of incidence-rate ratios

So, I want to fit a random effects negative-binomial model. For such a model STATA can produce exponentiated coefficients. According to the help file such coefficients can be interpreted as incidence-rate ratios. Unfortunately I am not a native English speaker and I do not really understand what incidence-rate ratios are or how I could translate them.

So my question is, how can I interpret incidence-rate ratios. E.g.:

If the model gives me an incidence-rate ratios of .7 for one var. would that mean that the number of expected observations (counts) on the dependent var. changes by .7 if the independent var changes by one unit?

Can anyone help?

`counts = exp(B0 + B1*X)`, where B0 is the intercept term, B1 is the coefficient for your variable (equal in this example to ~-0.3365) and X is the value of X for whatever group you’re trying to calculate this for. I find that’s occasionally a useful sanity check to make sure I haven’t done something horribly wrong in the model itself.