ci.moments: Confidence intervals for Directly Standardised Rates using...

In mnel/dsrci: Confidence Intervals on Directly Standardized Rates for Several Parameterizations

Description

Confidence intervals for directly standardized rates based on the approximation proposed by Dobson, Kuulasmaa, Eberle and Scherer (1991). In addition to the method proposed by Dobson et al, the various approximations implemented by Ng, Filardo & Zheng (2008) are implemented.

Usage

ci.moments(x, w, level, type = c("dobson", "boise.monson", "normal",
  "wilson.hilferty", "byar", "midp", "approx.midp", "simple.midp"))

Arguments

x	a vector of stratum-specific counts of events
w	a vector of stratum-specific weights
level	confidence level for the returned confidence interval
type	type of approximation for the poisson confidence interval of the unweighted sum

Details

Following Dobson et al (1991), an approximate confidence interval can be obtained as a linear function of the confidence interval for a single Poisson paramenter (X = ∑_{i=1}^k X_i) where the confidence interval for this unweighted sum of poisson parameters ∑_{i=1}^k θ_i is (X_L,X_U). An approximate confidence interval for the weighted sum of θ is

T_L=√(υ/y)(X_L-X)

T_U=√(υ/y)(X_U-X)

A number of methods for estimating (X_L,X_U) are implemented in dsrci

• Dobson (exact): type = "dobson" (Ng et al method M1)

• Boise-Monson: type = "boise.monson" (Ng et al method M2)

• Normal approximation: type = "normal" (Ng et al method M3)

• Wilson-Hilferty: type = "wilson.hilferty" (Ng et al method M4)

• Byar: type = "byar" (Ng et al method M5)

• Exact Mid-p type = "midp" (Ng et al method M7) - implemented using exactci::poison.exact

• Approximation to Mid-p: type = "approx.midp" (Ng et al method M8)

• Simple approximation to Mid-p: type = "simple.midp" (Ng et al method M9)

Value

a vector with the lower and upper bound of the confidence interval. The estimate of the directly standardised rate and the level of confidence are returned as attributes to this vector.

References

Dobson, AJ, Kuulasmaa, K, Eberle, E and Scherer, J (1991) 'Confidence intervals for weighted sums of Poisson parameters', Statistics in Medicine, 10: 457–462. doi: 10.1002/sim.4780100317

Ng, Filardo, & Zheng (2008). 'Confidence interval estimating procedures for standardized incidence rates.' Computational Statistics and Data Analysis 52 3501–3516. doi: 10.1016/j.csda.2007.11.004

Fay MP (2010). 'Two-sided Exact Tests and Matching Confidence Intervals for Discrete Data'. R Journal 2(1):53–58. exactci

mnel/dsrci documentation built on May 23, 2019, 5:06 a.m.