What are the warning Westgard rules?
Westgard rules
| Rule | Criteria |
|---|---|
| R4s | Two measurements in the same run have a 4 standard deviation difference (such as one exceeding 2 standard deviations above the mean, and another exceeding 2 standard deviations below the mean). |
| 41s | 4 consecutive measurements exceed 1 standard deviation on the same side of the mean. |
What are the Westgard rules that indicate random errors are present?
Random error is usually indicated by the 13s or R4srules, whereas systematic error is more likely indicated by the 22s,41s, or 10x rules. Refer to trouble-shooting guides to identify possible causes for the type of error indicated by the control rule that was violated.
What is Westgard rule?
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.
What is the r4s rule?
Westgard Rule R. 4s The R4s rule applies to controls within a run. If two controls exceed 4SD, that is, if one control exceeds +2SD and the other control (or another control, if more than 2 controls are tested) exceeds -2SD, the run should be rejected.
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 advantage of using Westgard Multirules?
The advantages of multirule QC procedures are that false rejections can be kept low while at the same time maintaining high error detection. This is done by selecting individual rules that have very low levels of false rejection, then building up the error detection by using these rules together.
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 control out of acceptable 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.
How are Westgard Rules calculated?
To calculate cumulative control limits, enter the previous month’s figures for n, sum of x, and sum of x squared, then push the “Total” button. To calculate monthly control limits, just push the “Total” button and only the monthly figures will be used.
How do you reduce random error?
Random error can be reduced by:
- Using an average measurement from a set of measurements, or.
- Increasing sample size.
When does Westgard rule 2s need to be rejected?
Westgard rule 2 2s states that if two consecutive control measurements across runs exceed the same mean -2 standard deviations (SD) or exceed the same mean +2SD, or, within a run, if two consecutive control values are outside the same 2 SD, the run must be rejected.
How are the Westgard rules used in multirules?
In the original Westgard multirule QC procedure, this rule is used as a warning rule to trigger careful inspection of the control data by the following rejection rules. 22s – reject when 2 consecutive control measurements exceed the same mean plus 2s or the same mean minus 2s control limit.
What is the short hand notation for Westgard rules?
For convenience, we adopt a short hand notation to abbreviate different decision criteria or control rules, e.g., 1 2s to indicate 1 control measurement exceeding 2s control limits.
What should be the sigma limit for Westgard?
For methods having sigmas between 4.5 and 5.5, you need to be more careful in your selection of QC procedures. At the high side (5.0 to 5.5), you can generally use 2.5s control limits with an N of 2 or 3. At the low side (4.5 to5.0), you should use an N of 4.