For the horseshoe crab data, the following output shows a zero-inflated negative binomial model using quantitative color for the zero component. Interpret results, and compare with the NB2 model fitted in the previous exercise with quantitative color. Can you conduct a likelihood-ratio test comparing them?

Why or why not?

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> summary(zeroinfl(y ~ 1 | color, dist = "negbin")) # Using Crabs.dat Count model coefficients (negbin with log link):

Estimate Std. Error z value Pr(>|z|)

(Intercept) 1.4632 0.0689 21.231 < 2e-16 Log(theta) 1.4800 0.3511 4.215 2.5e-05 Zero-inflation model coefficients (binomial with logit link):

Estimate Std. Error z value Pr(>|z|)

(Intercept) -2.7520 0.6658 -4.133 3.58e-05 color 0.8023 0.2389 3.358 0.000785

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Theta = 4.3928 Log-likelihood:-362.997 on 4 Df