covar {healthequal}

Coefficient of variation (COV)

Description

The Coefficient of Variation (COV) is a relative measure of inequality that considers all population subgroups. Subgroups are weighted according to their population share.

Usage

covar(pop, est, se = NULL, scaleval, sim = NULL, seed = 123456, ...)

Arguments

pop

The number of people within each subgroup. Population size must be available for all subgroups.

est

The subgroup estimate. Estimates must be available for all subgroups.

se

The standard error of the subgroup estimate. If this is missing, 95% confidence intervals of COV cannot be calculated.

scaleval

The scale of the indicator. For example, the scale of an indicator measured as a percentage is 100. The scale of an indicator measured as a rate per 1000 population is 1000.

sim

The number of simulations to estimate 95% confidence intervals

seed

The random number generator (RNG) state for the 95% confidence interval simulation

...

Further arguments passed to or from other methods.

Details

COV is calculated by dividing the between-group standard deviation (BGSD) by the setting average and multiplying the fraction by 100. BGSD is calculated as the square root of the weighted average of squared differences between the subgroup estimates and the setting average. Squared differences are weighted by each subgroup’s population share. For more information on this inequality measure see Schlotheuber, A., & Hosseinpoor, A. R. (2022) below.

95% confidence intervals are calculated using a methodology of simulated estimates. The dataset is simulated a large number of times (e.g., 100) and COV is calculated for each of the simulated samples. The 95% confidence intervals are based on the 2.5th and 97.5th percentiles of the COV results.

Interpretation: COV only has positive values, with larger values indicating higher levels of inequality. COV is zero if there is no inequality.

Type of summary measure: Complex; relative; weighted

Applicability: Non-ordered; more than two subgroups

Value

The estimated COV value, corresponding estimated standard error, and confidence interval as a data.frame.

References

Schlotheuber, A., & Hosseinpoor, A. R. (2022). Summary measures of health inequality: A review of existing measures and their application. International Journal of Environmental Research and Public Health, 19 (6), 3697.

Examples

# example code
data(NonorderedSample)
head(NonorderedSample)
with(NonorderedSample,
     covar(pop = population,
            est = estimate,
            se = se,
            scaleval = indicator_scale
           )
     )