-#' ID method\r
-#'\r
-#' This function implements a least squares estimation method of R0 due to Fisman et al. (PloS One, 2013).\r
-#' See details for implementation notes.\r
-#'\r
-#' The method is based on a straightforward incidence decay model. The estimate of R0 is the value which\r
-#' minimizes the sum of squares between observed case counts and cases counts 'expected' under the model.\r
-#'\r
-#' This method is based on an approximation of the SIR model, which is most valid at the beginning of an epidemic.\r
-#' The method assumes that the mean of the serial distribution (sometimes called the serial interval) is known.\r
-#' The final estimate can be quite sensitive to this value, so sensitivity testing is strongly recommended.\r
-#' Users should be careful about units of time (e.g. are counts observed daily or weekly?) when implementing.\r
-#'\r
-#' @param NT Vector of case counts\r
-#' @param mu Mean of the serial distribution (needs to match case counts in time units; for example, if case counts are\r
-#' weekly and the serial distribution has a mean of seven days, then \code{mu} should be set to one, if case\r
-#' counts are daily and the serial distribution has a mean of seven days, then \code{mu} should be set to seven)\r
-#'\r
-#' @return \code{ID} returns a list containing the following components: \code{Rhat} is the estimate of R0 and\r
-#' \code{inputs} is a list of the original input variables \code{NT, mu}.\r
-#'\r
-#' @examples\r
-#'\r
-#' ## ===================================================== ##\r
-#' ## Illustrate on weekly data ##\r
-#' ## ===================================================== ##\r
-#'\r
-#' NT <- c(1, 4, 10, 5, 3, 4, 19, 3, 3, 14, 4)\r
-#' ## obtain Rhat when serial distribution has mean of five days\r
-#' res1 <- ID(NT=NT, mu=5/7)\r
-#' res1$Rhat\r
-#' ## obtain Rhat when serial distribution has mean of three days\r
-#' res2 <- ID(NT=NT, mu=3/7)\r
-#' res2$Rhat\r
-#'\r
-#' ## ========================================================= ##\r
-#' ## Compute Rhat using only the first five weeks of data ##\r
-#' ## ========================================================= ##\r
-#'\r
-#'\r
-#' res3 <- ID(NT=NT[1:5], mu=5/7) # serial distribution has mean of five days\r
-#' res3$Rhat\r
-#'\r
-#' @export\r
-ID <- function(NT, mu) {\r
- NT <- as.numeric(NT)\r
- TT <- length(NT)\r
- s <- (1:TT) / mu\r
- y <- log(NT) / s\r
-\r
- R0_ID <- exp(sum(y) / TT)\r
-\r
- return(list=c(Rhat=R0_ID, inputs=list(NT=NT, mu=mu)))\r
-}\r
+#' ID method
+#'
+#' This function implements a least squares estimation method of R0 due to Fisman et al. (PloS One, 2013).
+#' See details for implementation notes.
+#'
+#' The method is based on a straightforward incidence decay model. The estimate of R0 is the value which
+#' minimizes the sum of squares between observed case counts and cases counts 'expected' under the model.
+#'
+#' This method is based on an approximation of the SIR model, which is most valid at the beginning of an epidemic.
+#' The method assumes that the mean of the serial distribution (sometimes called the serial interval) is known.
+#' The final estimate can be quite sensitive to this value, so sensitivity testing is strongly recommended.
+#' Users should be careful about units of time (e.g., are counts observed daily or weekly?) when implementing.
+#'
+#' @param NT Vector of case counts.
+#' @param mu Mean of the serial distribution. This needs to match case counts in time units. For example, if case counts
+#' are weekly and the serial distribution has a mean of seven days, then \code{mu} should be set to one If case
+#' counts are daily and the serial distribution has a mean of seven days, then \code{mu} should be set to seven.
+#'
+#' @return \code{ID} returns a single value, the estimate of R0.
+#'
+#' @examples
+#' ## ===================================================== ##
+#' ## Illustrate on weekly data ##
+#' ## ===================================================== ##
+#'
+#' NT <- c(1, 4, 10, 5, 3, 4, 19, 3, 3, 14, 4)
+#' ## obtain Rhat when serial distribution has mean of five days
+#' ID(NT=NT, mu=5/7)
+#' ## obtain Rhat when serial distribution has mean of three days
+#' ID(NT=NT, mu=3/7)
+#'
+#' ## ========================================================= ##
+#' ## Compute Rhat using only the first five weeks of data ##
+#' ## ========================================================= ##
+#'
+#' ID(NT=NT[1:5], mu=5/7) # serial distribution has mean of five days
+#'
+#' @export
+ID <- function(NT, mu) {
+ NT <- as.numeric(NT)
+ TT <- length(NT)
+ s <- (1:TT) / mu
+ y <- log(NT) / s
+
+ R0_ID <- exp(sum(y) / TT)
+
+ return(R0_ID)
+}