What is R 4s rule?

The R 4s rule identifies random error. It is applied only within the current run. This rule is violated when there is at least a 4SD difference between control values within a single run. For example, assume both Level 1 and Level 2 have been tested within the current run.

What is the R4s rule?

R4s indicates a rejection when one control measurement in a run exceeds a +2s control limit and another exceeds a -2s control limit. This “range” rule is sensitive to changes in the width of the distribution, therefore it is a good indicate of increases in random error or changes in the precision of the method.

What are the warning Westgard rules?

One measurement exceeds 2 standard deviations either above or below the mean of the reference range. One measurement exceeds 3 standard deviations either above or below the mean of the reference range.

How do I apply for Westgard rules?

Stop if two points in a row exceed the same 2s limit. Stop if one point in the group exceeds a plus 2s limit and another exceeds a minus 2s limit. Because N must be at least 2 to satisfy US CLIA QC requirements, all these rules can be applied within a run.

What is CV in QC?

CV refers to the “coefficient of variation,” which describes the standard deviation as a percentage of the mean, as shown in the following equation: CV = (s/ )100.

What to do if QC is out of range?

If the repeat value is still out of range, run a new vial of control. If the new control value is within acceptable limits, record the values and proceed with patient testing. The problem with the first set of controls was probably specimen deterioration.

What is 1SD 2SD 3SD?

The larger the SD the more variance in the results. Data points in a normal distribution are more likely to fall closer to the mean. In fact, 68% of all data points will be within ±1SD from the mean, 95% of all data points will be within + 2SD from the mean, and 99% of all data points will be within ±3SD.

What are Westgard Multirules?

Westgard Rules are multirule QC rules to help analyze whether or not an analytical run is in-control or out-of-control. It uses a combination of decision criteria, usually 5 different control rules to judge the acceptability of an analytical run.

How do you calculate CV?

The formula for the coefficient of variation is: Coefficient of Variation = (Standard Deviation / Mean) * 100. In symbols: CV = (SD/x̄) * 100. Multiplying the coefficient by 100 is an optional step to get a percentage, as opposed to a decimal.

What is a good CV value?

Basically CV<10 is very good, 10-20 is good, 20-30 is acceptable, and CV>30 is not acceptable.

What is POC QC?

external quality assurance (EQA) are. integral components of the. laboratory quality system. • These tools ensure that the quality of results will not compromise the clinical care of the patient.

What is the difference between QC and calibration?

Calibration is the process by which we determine the intensity of the signal we measure when we analyze a sample of known concentration. The control (or internal control) is a procedure by which we verify that the calibration is valid. …

What does the 1 3s rule mean in math?

1 3s rule would mean that (one observation), a single run exceeds the mean plus 3SD or the mean minus 3SD (positive/negative) ± 3SD control limit. Or one value lies outside the mean ± 3SD.

How is the 1 3s rule used in QC?

Use of the 1 3s rule together with the 2 2s and R 4s rules leads to a multirule QC procedure in which multiple decision criteria are applied simultaneously. If any single control rule is violated, the run is rejected. Here’s how the 1 3s /2 2s /R 4s multirule procedure would be interpreted for this example set of control results:

When does a run violate the 3s rule?

 1 3s rule would mean that (one observation), a single run exceeds the mean plus 3SD or the mean minus 3SD (positive/negative) ± 3SD control limit. Or one value lies outside the mean ± 3SD. Therefore, the run must be rejected because this is a rule violation and measurement exceeds the limit.  2 2s rule requires control data from previous runs.

What happens if you use a 1 3s rejection rule?

Use of a 1 3s rejection rule would lead to rejection of only one run on day 5, as shown by the single check mark in the column for 1 3s rule violations. It makes a big difference what control rule is being applied — 9 rejections vs 1 rejection! What if different control rules were used?