1. Data Entry:

   The user enters relevant information such as the analyst's name, control name, and the date/month of analysis. Additionally, the user inputs a series of control values obtained from quality control samples.
2. Calculation:

   Upon clicking the "Calculate" button, the application computes statistical parameters such as the mean, standard deviation (SD), and coefficient of variation (CV) of the input values.
3. Quality Control Rules Check:

   The application applies Westgard rules to the entered data to identify any out-of-control conditions.
4. Chart Generation:

   A Levey-Jennings chart is produced, displaying control values against time or sample number, with lines representing the mean and control limits based on standard deviations.
5. Violation Reporting:

   If any quality control rules are violated, the specific instances are reported to the user, allowing for investigation and corrective action.
6. Print and Show Violations:

   Users can print the generated chart and view detailed violations.

The calculator applies the full Westgard multi-rule set. Rules are judged against the target mean and SD when you enter them (from the control insert or your established values), otherwise against this batch’s own mean and SD (n−1).

1. 1_2s — warning

   One value beyond ±2 SD. Not a rejection on its own; it calls for a look at the other rules.
2. 1_3s — reject

   One value beyond ±3 SD. Random error.
3. 2_2s — reject

   Two consecutive values beyond 2 SD on the same side. Systematic error.
4. 2of3_2s — reject

   Two of three consecutive values beyond 2 SD on the same side. Systematic error.
5. R_4s — reject

   One value beyond +2 SD and the next beyond −2 SD (or the reverse), a range over 4 SD. Random error.
6. 3_1s — reject

   Three consecutive values beyond 1 SD on the same side. Systematic error.
7. 4_1s — reject

   Four consecutive values beyond 1 SD on the same side. Systematic error.
8. 7_T — reject

   Seven consecutive values rising or falling. A trend.
9. 8x / 10x / 12x — reject

   Eight, ten or twelve consecutive values on the same side of the mean. A shift. A value exactly on the mean breaks the run.

Each run is reported once, from its first to its last value; the chart marks every value involved.

Understanding the Output

Once you input the data and press "Calculate," the calculator will output:

• Mean: The average of your control values, representing the expected value in a stable process.
• SD (Standard Deviation): A measure of the variability or dispersion of the control values. A higher SD indicates greater variation in the results.
• CV (Coefficient of Variation): Expressed as a percentage, the CV represents the ratio of the standard deviation to the mean, providing a scaled measure of variability relative to the size of the mean.

Chart Interpretation

The Levey-Jennings chart plots individual control values against time or sample number. The mean value is marked as a central line, with additional lines representing the mean ±1 SD, ±2 SD, and ±3 SD. Points outside these lines indicate potential violations of Westgard rules and warrant investigation.

Troubleshooting

Common issues include:

• Input Errors: Ensure all values are numerical and separated by commas. Check for extra spaces or characters.
• Misalignment: If elements on the page are misaligned, especially on different screen sizes, verify the CSS and Bootstrap grid classes for consistent styling.

Compliance Standards

The calculator adheres to standards set by CLIA, CAP, and ISO, which require rigorous QC to ensure laboratory test accuracy. Compliance with these standards is critical to meet regulatory requirements and maintain the quality of laboratory testing.