CAN'T MISS: conquer any number task by making important statistics simple. Part 7. Statistical process control: x-s control charts

The use of statistical control charts to monitor and improve the management of education department resources

Educators are responsible for the management of resources. Statistical control charts (SCCs) may be used by educators to improve resource utilization. In this article, the author describes the use of SCCs and presents a case study that demonstrates the power of SCCs to monitor processes and outcomes, to prompt change, and to be used as an effective presentation tool.

Population Control Charts for Population Data

Healthcare managers are beginning to collect full population data, rather than sample data, on some patient and performance measures. For example, hospitals and healthcare systems already gather and store comprehensive data on admissions, ambulatory encounters, and other procedures. And as the electronic medical record is more widely used, complete population data will be collected on an even wider range of clinical measures, such as blood pressure and Laboratory values, in both inpatient and outpatient settings. To correctly monitor process quality when working with full population data, rather than sample data, healthcare managers will need appropriate statistical tools. Traditional control charts, which are used for tracking processes over time, are not suitable for such population data because they are based on the assumption that sample data are being collected. The author proposes a new type of control chart specifically for use with such population data: population control charts. These control charts can be used for monitoring processes that have output measures with continuous, binomial, or nonbinomial rate variables.

CAN'T MISS: conquer any number task by making important statistics simple. Part 8. Statistical process control: n, np, c, u control charts

A p control chart is used to monitor a proportion from a binomial variable that reflects the output of a process. The p control chart is a graph that includes serial sample proportions (p) as the variables of interest, a centerline that represents the overall proportion of the samples (p), and upper control limits (UCLs) and Lower control Limits (LCLs) that represent three standard errors (SEp) above and below the centerline. We use a p control chart to estimate with 99.7% confidence that the population proportion of an output variable was within the interval defined by the UCLs and LCLs during a period of baseline monitoring. We further assume that if the process remains stable, the values of future population proportions will remain between the established control limits. An np control chart simply plots the numerators of the sample proportions as the variables of interest. A u control chart is used to monitor ratios. In u control charts, ratios are quantities in which the numerator can have one or more occurrences in reference to the denominator. A c control chart is analogous to an np control chart in that it graphs the numerators from the ratios.