The P Chart plots the percentages for each period as a point on the line. The percentage is the total numerator for that period (Total Beta Blockers Administered Prior to Arrival) divided by the total denominator of that period (Total eligible for Beta Blockers). This chart uses a sigma determined by the number of points plotted on the chart.
This analysis type, P Chart, automatically calculates the number of sigmas to use to calculate the control limits, depending on the number of periods display. See T Table for further information.
The P chart addresses those indicators where we are measuring one of two possible outcomes of an event. Often, compliance indicators come to mind for these types of charts. For example, "Beta Blockers Prior to Arrival": For each patient arriving, did they receive beta blocker prior to arrival?
The numerator is the number of patient receiving beta blockers and the denominator is the number arriving. The numerator is a subset of the patients in the denominator and the resulting percentage cannot exceed 100%.
Other chart available for the Percentage Type are Bar Chart, P Chart 3-Sigma, P Chart 2-Sigma, Bar Chart with Cumulative, Run Chart and Trend Chart.