Prevalence ratio

Formula: PR = p_e / p_u; se(log PR) = sqrt((1-p_e)/(p_e n_e) + (1-p_u)/(p_u n_u))

Usage

Prevratio(
  prev_exposed,
  prev_unexposed,
  n_exposed = NULL,
  n_unexposed = NULL,
  alpha = 0.05
)

Arguments

prev_exposed

See Usage.

prev_unexposed

See Usage.

n_exposed

See Usage.

n_unexposed

See Usage.

alpha

See Usage.

Value

List with pr, log_pr, se_log, ci_lower, ci_upper.

References

Barros and Hirakata (2003), Alternatives for logistic regression in cross-sectional studies: an empirical comparison of models that directly estimate the prevalence ratio, BMC Medical Research Methodology 3:21. Open access; the delta-method standard error for log PR used here is the standard binomial one.

Examples

Prevratio(prev_exposed = 0.3, prev_unexposed = 0.15, n_exposed = 200, n_unexposed = 300)
#> $pr
#> [1] 2
#> 
#> $log_pr
#> [1] 0.6931472
#> 
#> $se_log
#> [1] 0.1748015
#> 
#> $ci_lower
#> [1] 1.419838
#> 
#> $ci_upper
#> [1] 2.817223
#> 
#> $method
#> [1] "Prevalence ratio"
#> 
#> attr(,"class")
#> [1] "morie_rich_result" "list"