Statistical analysis
The Steering Committee expects that statistical analysis should be relevant and easy to follow. Participants have echoed this view that simple analysis with, if appropriate, graphical display, are vital.
The majority of analyses are based on a deviation index (DI) from a mean or median value:
DI = Result – Mean
Standard Deviation
Participants are divided into method groups where there are sufficient numbers (n=>5), and thus receive both overall and group data.
The method group DI is used for continuous assessment of data unless the participant is using a method with too few users to establish a separate group analysis. In this case the DI from the overall mean is employed.