sim_single_pd: The estimated value of detection probability at a single...

In Mayooran1987/mixingsimulation: Microbiological Risk Assessment of Powder Mixing Process by Simulation Results

The estimated value of detection probability at a single stage (or revolution) of the mixing process.

Description

This function gives a probability of detection at a single stage (or revolution) of the mixing process.

Usage

sim_single_pd(mu, sigma, alpha, k, distribution, UDL, n_sim)

Arguments

mu	the average number of CFUs (\mu) in the mixed sample, which is in a logarithmic scale if we use a Lognormal / Poisson lognormal distribution
sigma	the standard deviation of the colony-forming units in the mixed sample on the logarithmic scale (default value 0.8)
alpha	concentration parameter
k	number of small portions / primary samples
distribution	what suitable distribution type we have employed for simulation such as "Poisson-Type A" or "Poisson-Type B" or "Lognormal-Type A" or "Lognormal-Type B" or "Poisson lognormal-Type A" or "Poisson lognormal-Type B"
UDL	the upper decision limit, which depends on the type of microorganisms and testing regulations.
n_sim	number of simulations

Details

Let N' be the number of CFUs in the mixed sample, which is produced by the contribution of k primary samples mixing, N' = \sum N_i and let l be the number of stages in the mixing process. This function provides the probability of detection at each stage of the mixing process. The probability of detection can be determined by how many primary samples contain CFUs greater than UDL out of the number of primary samples engaged at each mixing stage.

Therefore, the probability of detection (p_d) can be estimated from following formula,

p_d = \frac{\textnormal{Number of primary samples which contain CFUs greater than UDL}}{\textnormal{Number of primary samples}} ;

where the upper decision limit (UDL) depends on microorganisms and testing regulations. For example, UDL should be equal to 0 for testing Salmonella in milk powder sample if we consider 25g primary sample.

Value

The probability of detection at each stage of the mixing process.

References

• Nauta, M.J., 2005. Microbiological risk assessment models for partitioning and mixing during food handling. International Journal of Food Microbiology 100, 311-322.

See Also

sim_single_stages

Examples

mu <- 100
sigma <- 0.8
alpha <- 0.1
k <- 30
distribution <-  "Poisson lognormal-Type B"
UDL <- 0
n_sim <- 2000
sim_single_pd(mu, sigma , alpha , k, distribution, UDL, n_sim)

Mayooran1987/mixingsimulation documentation built on May 12, 2023, 12:36 a.m.