calculate_I_mixed: Function to calculate incidence from PPS data using a mix of...

In prevtoinc: Prevalence to Incidence Calculations for Point-Prevalence Studies in a Nosocomial Setting

Function to calculate incidence from PPS data using a mix of two estimators

Description

A sigmoid function with parameters a and b (see below) is used to get weights for a combination of the two estimator for x.loi and x.los.

Usage

calculate_I_mixed(I.pps.1, I.pps.2, a = 0.01, b = 500, method = "pps.mixed")

Arguments

I.pps.1	resulting data frame for first estimator
I.pps.2	resulting data frame for second estimator
a	parameter a for the sigmoid function
b	parameter b for the sigmoid function
method	name of the method

Details

is achieved in the following way for estimation of x.loi alpha = exp(a*(n.noso-b))/(1+exp(a*(n.noso-b))) x.loi.hat.mixed = alpha*x.loi.hat.1 + (1-alpha)*x.loi.hat.2

alpha = exp(a*(n-b))/(1+exp(a*(n-b))) x.los.hat.mixed = alpha*x.los.hat.1 + (1-alpha)*x.los.hat.2

Value

one-row data frame with following columns

n	number of patients sampled
n.noso	number of HAIs
P.hat	estimate of prevalence P
I.hat	estimate of incidence rate I
I.pp.hat	estimate of incidence proportion per admission I.pp
x.loi.hat	estimate of x.loi
x.los.hat	estimate of x.los
method	name of the method

Examples

# create example data for PPS
example.dist <- create_dist_vec(function(x) dpois(x-1, 7), max.dist = 70)
example.dist.los <- create_dist_vec(function(x) dpois(x-1, lambda = 12),
                                    max.dist = 70)
data.pps.fast <- simulate_pps_fast(n.sample=200,
                                   P=0.05,
                                   dist.X.loi = example.dist,
                                   dist.X.los = example.dist.los)
head(data.pps.fast)

# estimate of incidence
I.1 <- calculate_I_smooth(data = data.pps.fast,
                   method = "gren")
                   
# estimate incidence based on Rhame-Sudderth formula
I.2 <- calculate_I_rhame(data = data.pps.fast,
                   x.loi.hat = 8,
                   x.los.hat = 13)

# mixed estimator                                      
calculate_I_mixed(I.1, I.2)

prevtoinc documentation built on Sept. 3, 2026, 5:07 p.m.