Interpreting Your Results
Carryover Analysis Results
The results panel displays the following statistics:
| Metric | What It Tells You |
|---|---|
| Low (Control) Mean | The mean of the 3 baseline Low specimens (positions 1–3). This is the reference value representing the true low concentration free of carryover contamination. |
| Low (Control) SD | The standard deviation of the 3 baseline Low specimens. Reflects normal variability in the low-concentration pool and is used in the Auto error limit calculation (3 × SD). |
| Low (Test) Mean | The mean of the 8 Low test specimens that follow High specimens. Elevated values relative to the control mean suggest carryover contamination from the preceding high-concentration measurements. |
| Low (Test) SD | The standard deviation of the 8 Low test specimens. Higher variability here than in the control group may indicate inconsistent carryover contamination across the sequence. |
| Carryover Mean | Low (Test) Mean minus Low (Control) Mean. The estimated average carryover contamination. A positive value indicates the test specimens are reading higher than baseline. A value near zero indicates minimal carryover. |
| Upper Confidence Limit | The upper bound of the 95% CI for the carryover estimate, calculated using the Welch-Satterthwaite degrees of freedom. This is the worst-case carryover with 95% confidence and is the value compared against the Error Limit for pass/fail. |
| Error Limit | The maximum acceptable carryover as configured (Auto = 3 × Control SD; Concentration = user-defined absolute; Percent = user-defined % of low concentration). |
| Result | PASS if Upper Confidence Limit < Error Limit; FAIL if Upper Confidence Limit ≥ Error Limit. |
Interpreting the Carryover Mean and UCL
The Carryover Mean alone does not determine pass/fail — the Upper Confidence Limit (UCL) does. Even a small Carryover Mean can produce a failing UCL if the variability in the test or control group is large, because the UCL widens with higher uncertainty. Conversely, a modest positive Carryover Mean may still pass if the data are consistent and the UCL remains below the error limit.
When interpreting a passing result, confirm that the UCL has meaningful margin below the error limit. A UCL very close to the error limit — even a passing one — warrants monitoring, particularly before testing high-concentration patient specimens in routine use.