Observe concentration measurements

This option fits the EpiSewer model to pathogen concentrations measured in wastewater samples. It is suitable for different quantification methods such as qPCR or dPCR. The measured concentrations are modeled via a Log-Normal likelihood.

Usage

concentrations_observe(
  measurements = NULL,
  composite_window = 1,
  distribution = "gamma",
  date_col = "date",
  concentration_col = "concentration",
  replicate_col = NULL,
  n_averaged = 1,
  n_averaged_col = NULL,
  total_partitions_col = NULL,
  modeldata = modeldata_init()
)

Arguments

measurements: A data.frame with each row representing one measurement. Must have at least a column with dates and a column with concentration measurements.
composite_window: Over how many days has each measured sample been collected? If 1 (default), samples represent single days. If larger than 1, samples are assumed to be equivolumetric composites over several dates. In this case, the supplied dates represent the last day included in each sample.
distribution: Parametric distribution for concentration measurements. Currently supported are "gamma" (default and recommended), "log-normal", "truncated normal", and "normal". The "truncated normal" and "normal" options are not recommended for use in practice.
date_col: Name of the column containing the dates.
concentration_col: Name of the column containing the measured concentrations.
replicate_col: Name of the column containing the replicate ID of each measurement. This is used to identify multiple measurements made of a sample from the same date. Should be NULL if only one measurement per date was made.
n_averaged: The number of replicates over which the measurements have been averaged. This is typically used as an alternative to providing several replicates per sample (i.e. the concentration provided in the measurements data.frame is the arithmetic mean of several replicates). Can be either a single number (it is then assumed that the number of averaged replicates is the same for each observation) or a vector (one value for each observation).
n_averaged_col: Name of the column in the measurements data.frame containing the number of replicates over which the measurements have been averaged. This is an alternative to specifying n_averaged.
total_partitions_col: Name of the column in the measurements data.frame containing the total number of partitions (e.g. droplets for ddPCR) in the dPCR reaction of each measurement. Only applies to concentration measurements obtain via dPCR. Can be used by the noise_estimate_dPCR() and LOD_estimate_dPCR() modeling components. Note that this is really the total number of partitions, not just the number of positive partitions.
modeldata: A modeldata object to which the above model specifications should be added. Default is an empty model given by modeldata_init(). Can also be an already partly specified model returned by other EpiSewer modeling functions.

Value

A modeldata object containing data and specifications of the model to be fitted. Can be passed on to other EpiSewer modeling functions to add further data and model specifications.

The modeldata object also includes information about parameter initialization (init), meta data (.metainfo), and checks to be performed before model fitting (.checks).

Usage

Arguments

Value

See also