Median control charts -- also known as xtilde control charts -- are used to fill the vacuum between individuals charts and averages charts (xbar charts). Averages charts, accompanied by either range charts or sigma charts, are the SPC tool of choice for variables data. The advantages of using xbar charts include the normalizing effect of the central limit theorem, sensitivity at whatever level is desired by adjusting subgroup size, optimal estimation of process variation through rational subgrouping, graphical control of dispersion, and independence of points on the xbar chart, which makes run testing possible. When it is not possible to use xbar charts, individuals charts are usually employed along with the moving range chart.