Function to calculate confidence intervals
conf_int(df, analysis_result = "analysis_result", distribution = "distribution", method = "mvue", ci_type = "two-sided", conf_level = 0.95)
| df | df data frame of groundwater data in tidy format |
|---|---|
| analysis_result | the analysis result column |
| distribution | the distribution column |
| method | character string specifying the method of estimation. Possible values are "mvue" (minimum variance unbiased; the default), and "mle/mme" (maximum likelihood/method of moments). |
| ci_type | character string indicating what kind of confidence interval to compute. The possible values are ci_type="two-sided" (the default), ci_type="lower", and ci_type = "upper |
| conf_level | a scalar between 0 and 1 indicating the confidence level of the prediction interval. The default value is conf_level = 0.95 |
data("gw_data") wells <- c("MW-1", "MW-2", "MW-3", "MW-4") params <- c("Sulfate, total", "Arsenic, dissolved", "Boron, dissolved") background <- lubridate::ymd(c("2007-12-20", "2012-01-01"), tz = "UTC") # first group data by location, param, and background # estimate percent less than and distribution background_data <- gw_data %>% filter(location_id %in% wells, param_name %in% params, sample_date >= background[1] & sample_date <= background[2]) %>% group_by(location_id, param_name, default_unit) %>% percent_lt() %>% est_dist(., keep_data_object = TRUE) %>% arrange(location_id, param_name) background_data %>% conf_int(., ci_type = "lower", conf_level = 0.99)#> Warning: `cols` is now required. #> Please use `cols = c(sample_size, lcl, ucl, conf_level)`#> # A tibble: 12 x 8 #> # Groups: location_id, default_unit, param_name [12] #> location_id default_unit param_name distribution sample_size lcl ucl #> <chr> <chr> <chr> <chr> <int> <dbl> <dbl> #> 1 MW-1 ug/L Arsenic, … Nonparametr… 14 1.5 Inf #> 2 MW-1 mg/L Boron, di… Nonparametr… 14 0.265 Inf #> 3 MW-1 mg/L Sulfate, … Nonparametr… 14 50.4 Inf #> 4 MW-2 ug/L Arsenic, … Nonparametr… 14 1.38 Inf #> 5 MW-2 mg/L Boron, di… Lognormal 14 1.99 Inf #> 6 MW-2 mg/L Sulfate, … Nonparametr… 14 163. Inf #> 7 MW-3 ug/L Arsenic, … Nonparametr… 14 0.6 Inf #> 8 MW-3 mg/L Boron, di… Lognormal 14 1.29 Inf #> 9 MW-3 mg/L Sulfate, … Lognormal 14 126. Inf #> 10 MW-4 ug/L Arsenic, … Normal 14 4.36 Inf #> 11 MW-4 mg/L Boron, di… Normal 14 0.265 Inf #> 12 MW-4 mg/L Sulfate, … Nonparametr… 14 78.5 Inf #> # … with 1 more variable: conf_level <dbl>