Letter Values for the course Exploratory Data Analysis (MATD39) at
Federal University of Bahia (Brazil). The approach implemented in the
package is presented in the textbook of Montgomery and Runger (2010)
&lt;ISBN: 0-471-38491-7&gt;.

## Example

In this example, we’ve used the dataset `rivers`, which is available in
`R` and it is a `vector`.

    library(lettervalue)
    letter_value(rivers)

    ## n = 141
    ## 
    ##     rivers                
    ##     ----------------------
    ## M 71|        425         |
    ## F 36| 310           680  |
    ## 1 1 | 135           3710 |
