[R] Interpreting NB GLM output - effect sizes?

[Anna Berthinussen]

Hi,

I am trying to find out how to interpret the summary output from a neg
bin GLM?

I have 3 significant variables and I can see whether they have a
positive or negative effect, but I can't work out how to calculate the
magnitude of the effect on the mean of the dependent variable. I used
a log link function so I think I might have to use the antilogs of the
coefficients but I have no idea how this relates to the dependent
variable??

Any help would be much appreciated.

My model and output is shown below.

Thanks

Anna

Call:
glm.nb(formula = Pass ~ Dist + Time + Wind, data = bats, link = "log",
       init.theta = 0.8510838809)

Deviance Residuals:
       Min       1Q   Median       3Q      Max
-2.2784  -0.9967  -0.3594   0.2603   2.2142

Coefficients:
                 Estimate Std. Error z value Pr(>|z|)
(Intercept)  3.3329718  0.3603909   9.248  < 2e-16 ***
Dist         0.0008892  0.0002377   3.741 0.000183 ***
Time        -0.0159068  0.0034665  -4.589 4.46e-06 ***
Wind        -0.1177475  0.0346301  -3.400 0.000673 ***
---
Signif. codes:  0 ?***? 0.001 ?**? 0.01 ?*? 0.05 ?.? 0.1 ? ? 1

(Dispersion parameter for Negative Binomial(0.8511) family taken to be 1)

       Null deviance: 134.586  on 79  degrees of freedom
Residual deviance:  92.725  on 76  degrees of freedom
AIC: 501.21

Number of Fisher Scoring iterations: 1


                 Theta:  0.851
             Std. Err.:  0.164

    2 x log-likelihood:  -491.211