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# EpiStandard <img src="man/figures/hexsticker.png" align="right" style="width:25%;"/>

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The goal of EpiStandard is to provide functions to allow for age
standardisation of results produced from epidemiological studies.

## Installation

The package can be installed from CRAN:

``` r
install.packages("EpiStandard")
```

You can install the development version of EpiStandard from
[GitHub](https://github.com/) with:

``` r
# install.packages("devtools")
devtools::install_github("oxford-pharmacoepi/EpiStandard")
```

## Main functionalities

``` r
library(EpiStandard)
```

The main functionality of the package is to calculate directly
standardised rates.

### Example

``` r
 df_study <- data.frame(state=rep(c('Miami',"Alaska"), c(5,5)),
                       age=rep(c('0-14','15-24','25-44','45-64','65-150'),2),
                       deaths=c(136,57,208,1016,3605,59,18,37,90,81),
                       fu=c(114350,80259,133440,142670,92168,37164,20036,32693,14947,2077))

 #US standard population
 df_ref  <- data.frame(age=c('0-14','15-24','25-44','45-64','65-150'),
                      pop=c(23961000,15420000,21353000,19601000,10685000))

 #Directly standardised Rates (per 1000) - 95% CI's using the gamma method
 my_results <- directlyStandardiseRates(data = df_study,
                   event = "deaths",
                   denominator = "fu",
                   strata = "state",
                   age = "age",
                   refdata = df_ref)
 
 my_results |> dplyr::glimpse()
```

    ## Rows: 2
    ## Columns: 9
    ## $ state                        <chr> "Miami", "Alaska"
    ## $ deaths                       <dbl> 5022, 285
    ## $ fu                           <dbl> 562887, 106917
    ## $ crude_rate                   <dbl> 892.1862, 266.5619
    ## $ crude_rate_95CI_lower        <dbl> 867.5107, 235.6145
    ## $ crude_rate_95CI_upper        <dbl> 916.8616, 297.5093
    ## $ standardised_rate            <dbl> 692.4240, 671.0406
    ## $ standardised_rate_95CI_lower <dbl> 673.0405, 566.6666
    ## $ standardised_rate_95CI_upper <dbl> 711.8074, 775.4146
