Apply suggestions from code review

Co-authored-by: Sam Abbott <s.e.abbott12@gmail.com>

NEWS.md

@@ -25,7 +25,7 @@
 ## Model changes
 
 * Updated the parameterisation of the dispersion term `phi` to be `phi = 1 / sqrt_phi ^ 2` rather than the previous parameterisation `phi = 1 / sqrt(sqrt_phi)` based on the suggested prior [here](https://github.com/stan-dev/stan/wiki/Prior-Choice-Recommendations#story-when-the-generic-prior-fails-the-case-of-the-negative-binomial) and the performance benefits seen in the `epinowcast` package (see [here](https://github.com/epinowcast/epinowcast/blob/8eff560d1fd8305f5fb26c21324b2bfca1f002b4/inst/stan/epinowcast.stan#L314)). By @seabbs in # and reviewed by @sbfnk.
-* Added an `na` argument to `obs_opts()` that allows the user to specify whether NA values in the data should be interpreted as missing or accumulated in the next non-NA data point. By @sbfnk.
+* Added an `na` argument to `obs_opts()` that allows the user to specify whether NA values in the data should be interpreted as missing or accumulated in the next non-NA data point. By @sbfnk in #534 and reviewed by @seabbs.
 
 # EpiNow2 1.4.0
 

R/opts.R

@@ -480,7 +480,7 @@ obs_opts <- function(family = "negbin",
                      week_effect = TRUE,
                      week_length = 7,
                      scale = list(),
-                     na = "missing",
+                     na = c("missing", "accumulate"),
                      likelihood = TRUE,
                      return_likelihood = FALSE) {
   if (length(phi) != 2 || !is.numeric(phi)) {