Functions for making run charts `[Anhoej, Olesen (2014) <doi:10.1371/journal.pone.0113825>]` and basic Shewhart control charts `[Mohammed, Worthington, Woodall (2008) <doi:10.1136/qshc.2004.012047>]` for measure and count data. The main function, qic(), creates run and control charts and has a simple interface with a rich set of options to control data analysis and plotting, including options for automatic data aggregation by subgroups, easy analysis of before-and-after data, exclusion of one or more data points from analysis, and splitting charts into sequential time periods. Missing values and empty subgroups are handled gracefully.
