Hi, I am using a zero inflated Poisson to model a dependent variable. How do I find out whether the zero-inflated Poisson is a good approximation of the variable?
So far I have: > m1 <- zeroinfl(Join_Count_6m ~ 1, data = Megdata) > summary(m1) Call: zeroinfl(formula = Join_Count_6m ~ 1, data = Megdata) Pearson residuals: Min 1Q Median 3Q Max -1.1517 -1.1517 -1.1297 -0.1326 42.5377 Count model coefficients (poisson with log link): Estimate Std. Error z value Pr(>|z|) (Intercept) 7.002181 0.002889 2424 <2e-16 *** Zero-inflation model coefficients (binomial with logit link): Estimate Std. Error z value Pr(>|z|) (Intercept) -0.2846 0.1462 -1.947 0.0515 . --- Signif. codes: 0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1 Number of iterations in BFGS optimization: 6 Log-likelihood: -1.264e+05 on 2 Df However plot () and qqplot () both give error messages: > plot(m1) Error in xy.coords(x, y, xlabel, ylabel, log) : 'x' is a list, but does not have components 'x' and 'y' > qqplot(m1) Error in rank(x, ties.method = "min", na.last = "keep") : unimplemented type 'list' in 'greater' Many thanks, Meg Please don't print this e-mail unless you really need to. This e-mail message is confidential to the intended recipient at the email address to which it has been addressed. If the message has been received by you in error, it may not be disclosed to or used by anyone other than the intended addressee, nor may it be copied in any way. If it is not intended for you please inform us, immediately, then delete it from your system. If the content is not about the business of the organisation then the message is not from us nor is it sanctioned by us. Anything in this e-mail or its attachments which does not relate to SRUC's or SAC Commercial Limited's official business is neither given nor endorsed by SRUC or SAC Commercial Limited. SRUC A Charitable company limited by guarantee, Scottish Charity Number: SC003712. Registered in Scotland, Company Number: SC103046 - Registered Office: Peter Wilson Building, King's Buildings, West Mains Road, Edinburgh EH9 3JG SAC Commercial Limited, an SRUC company Registered in Scotland, Company Number: SC148684 - Registered Office: Peter Wilson Building, King's Buildings, West Mains Road, Edinburgh EH9 3JG -- View this message in context: http://r.789695.n4.nabble.com/zero-inflated-Poisson-goodness-of-fit-of-distribution-tp4679061.html Sent from the R help mailing list archive at Nabble.com. [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.