Interpreting Your Results
Analysis Summary
The Analysis Summary reports the overall LoB result along with descriptive statistics for both sample types:
| Metric | What It Tells You |
|---|---|
| Maximum LoB | The highest LoB calculated across all reagent lots tested. This is the primary reported result — the conservative, worst-case estimate of the blank measurement ceiling. |
| Blank Samples — Count | Total number of blank measurements included in the analysis. |
| Blank Samples — Mean | The arithmetic mean of all blank measurements. Reflects the central tendency of the blank distribution; elevated means may indicate non-specific signal or reagent interference. |
| Blank Samples — SD | The standard deviation of all blank measurements. Wider distributions (higher SD) result in a higher calculated LoB. |
| Low-Level Samples — Count | Total number of low-level measurements included in the analysis. |
| Low-Level Samples — Mean | The arithmetic mean of all low-level measurements. Provides context for how far the low-level samples are above the blank distribution. |
| Low-Level Samples — Pooled SD | Pooled standard deviation calculated from individual sample SDs, weighted by degrees of freedom (n−1). Represents within-sample measurement variability at near-zero concentrations across all low-level samples. |
Analysis by Reagent Lot
The per-lot section breaks down the LoB calculation for each individual reagent lot. For each lot, the following are reported:
| Metric | What It Tells You |
|---|---|
| Blank Sample Mean | Mean of all blank measurements for this lot. Separating by lot reveals whether one lot produces systematically higher blank readings than another. |
| Blank Sample SD | Standard deviation of blank measurements for this lot. A lot with higher SD will tend to produce a higher LoB. |
| LoB (this lot) | The LoB calculated using the selected method (nonparametric or parametric) for this lot's blank data only. Comparing LoB values across lots reveals lot-to-lot variability in blank performance. |
| Low-Level Pooled SD | Pooled SD from low-level samples for this lot, calculated as √(Σ((n−1) × SD²) / Σ(n−1)) across unique sample IDs. Each sample's SD is weighted by its degrees of freedom. |
When one lot's LoB is noticeably higher than the others, that lot is driving the maximum LoB result. Investigate whether that lot's blank measurements show unusual spread, elevated mean, or outlying values before concluding that the LoB reflects true reagent behavior rather than a data quality issue.
Blank Sample Distribution Histogram
The histogram displays the frequency distribution of all blank measurements, overlaid with the calculated LoB. Use the histogram to:
- Confirm distributional shape — A roughly symmetric, unimodal distribution is consistent with the assumptions underlying both methods. A bimodal or heavily skewed distribution may indicate mixed sample populations, reagent lot effects, or outlying measurements that warrant investigation.
- Visualize the LoB cutoff — The vertical marker at the LoB shows where approximately 95% of blank measurements fall below. A small number of blank readings will extend beyond this line — this is expected by design.
- Identify outliers — Isolated bars far from the main distribution suggest individual measurements that may reflect sample handling errors or instrument events. Review raw data before excluding any values.
Manufacturer Claim Comparison
If a manufacturer's LoB claim was entered during setup, the module compares the calculated Maximum LoB against the claim. The manufacturer's claim is verified when the laboratory's calculated LoB does not exceed the manufacturer's stated value. A calculated LoB above the manufacturer's claim indicates that the blank distribution in your laboratory is wider or higher than the manufacturer characterized — which may reflect population differences, environmental factors, or reagent handling.