Version 1.1.5: now issues error/warning for low or 0 sig2

pkg/DESCRIPTION

@@ -12,7 +12,7 @@ Description: The TRIM model is widely used for estimating growth and decline of
     at Statistics Netherlands by Jeroen Pannekoek. See
     <https://www.cbs.nl/en-gb/society/nature-and-environment/indices-and-trends--trim-->
     for more information about TRIM.
-Version: 1.1.4
+Version: 1.1.5
 Imports: methods, utils, stats, graphics, grDevices
 URL: https://github.com/markvanderloo/rtrim
 BugReports: https://github.com/markvanderloo/rtrim/issues

pkg/NEWS

@@ -1,3 +1,6 @@
+version 1.1.5
+- Now generates an error when the computed overdispersion is 0, and a warning when overdispersion < 1 (thanks to Oscar Ramírez for proving a data set where this happened)
+
 version 1.1.4
 - Fixed a bug caused by auto-removal of empty factorial sites (thanks to Tomás Murray)
 

pkg/R/trim_workhorse.R

@@ -732,6 +732,8 @@ trim_workhorse <- function(count, site.id, year, month=NULL, covars=data.frame()
     } else {
       df <- sum(nobs) - length(alpha) - length(beta) # degrees of freedom
       sig2 <<- if (df>0) sum(r^2, na.rm=TRUE) / df else 1.0
+      if (sig2 < 1e-7) stop("Overdispersion apparently 0; consider setting overdisp=FALSE")
+      if (sig2 < 1) warning(sprintf("Overdispersion %.1f <1; consider setting overdisp=FALSE", sig2), call.=FALSE)
     }
     if (!is.finite(sig2)) stop("Overdispersion problem")
   }