Interpreting Your Results
Statistics Summary
The Statistics Summary panel reports the LoQ at the overall and per-lot level:
| Metric | What It Tells You |
|---|---|
| Overall Limit of Quantitation | The maximum LoQ across all reagent lots tested. This is the primary reported result — the conservative, worst-case LoQ that ensures acceptable precision is guaranteed across all tested lots. |
| Lot N Limit of Quantitation | The LoQ calculated from the power model fitted to that lot's data only. Comparing per-lot LoQ values reveals lot-to-lot variability in low-end precision performance. The lot with the highest LoQ drives the overall result. |
Analysis by Concentration Level
The concentration level table provides the statistics underlying the power model fit. Each row represents one concentration level:
| Column | What It Tells You |
|---|---|
| Concentration Level | The label for this level (e.g., Level 1, Level 2). |
| Assigned Value | The known concentration for this level — the X-axis input to the power model. |
| N | The number of replicate measurements at this level included in the analysis. |
| Mean | The arithmetic mean of all replicate results at this level. Should be close to the Assigned Value; large discrepancies may indicate a calibration or sample preparation issue. |
| SD | The standard deviation of replicate results at this level. Directly used to calculate the Measured CV%. |
| Measured CV% | The observed coefficient of variation at this level: (SD / Mean) × 100. This is the actual measured precision data point plotted on the CV% plot. |
| Fitted CV% | The CV% predicted by the power model at this concentration. Represents the smoothed, model-based estimate of expected precision at this level. |
| 95% CI (Fitted CV%) | The 95% confidence interval around the fitted CV% estimate. Wider intervals at the extremes of the concentration range indicate greater uncertainty in the model's prediction at those levels. |
CV% Plot
The CV% plot visualizes the relationship between concentration and imprecision, and is the primary tool for interpreting the LoQ result. It contains:
- Measured CV% (blue circles) — The actual observed CV% at each concentration level from the replicate data. These are the raw data points the power model is fitted to.
- Fitted CV% (orange line) — The power model curve. A good fit follows the trend of the measured CV% points closely. Points systematically above or below the fitted line at certain concentrations suggest the power model may not be a perfect fit for this analyte's precision profile.
- CV% threshold (purple dashed line) — The horizontal acceptance threshold configured as the largest acceptable CV%. The LoQ is determined at the intersection of this line and the fitted curve.
- LoQ (green dashed vertical line) — The concentration where the fitted CV% curve crosses the threshold. Values to the right of this line meet the precision acceptance criterion; values to the left do not.
No LoQ line visible? If the fitted curve does not intersect the threshold within the tested range, the LoQ cannot be determined from the current data. See the "When LoQ Cannot Be Determined" section above for guidance on how to address this.