GIFSQ Tools · Module 4 — Microbiology Methods & Laboratory Operations · Tool 78 of 500
Log a microbiology laboratory deviation, score its risk on a 5 × 5 matrix, and flag it when it has been open more than 30 days.
Try sample values — fills the form with the worked example below.
Deviation log
Saved on this device only. Calculate a result first, then add it to the log.
| Date / time | Severity | Likelihood | Risk score | Risk class | Overdue |
|---|
–
Risk score (severity × likelihood)
–
Risk class
–
Overdue (> 30 days)
Equation: Risk score = severity × likelihood, each scored 1 to 5. Low: 1–6. Medium: 7–14. High: 15–25. Overdue when days open > 30.
Method: 5 × 5 risk matrix as used in laboratory quality management for nonconforming work and corrective action under ISO/IEC 17025, with severity scored on the effect on results and likelihood on the chance of recurrence.
Assumptions: severity and likelihood are scored by the person who investigated the deviation, using the laboratory's own scoring guide.
Limitations: a risk score is a judgement aid, not a measurement — two people can score the same deviation differently, and a low score never excuses an uncorrected error. The 30-day overdue flag is a laboratory policy threshold, not a standard value.
Rounding: the risk score is a whole number from 1 to 25; no rounding is applied.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: 5 × 5 risk matrix as used in laboratory quality management for nonconforming work and corrective action under ISO/IEC 17025, with severity scored on the effect on results and likelihood on the chance of recurrence.
Assumptions: severity and likelihood are scored by the person who investigated the deviation, using the laboratory's own scoring guide.
Limitations: a risk score is a judgement aid, not a measurement — two people can score the same deviation differently, and a low score never excuses an uncorrected error. The 30-day overdue flag is a laboratory policy threshold, not a standard value.
Rounding: the risk score is a whole number from 1 to 25; no rounding is applied.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: Severity 3, likelihood 3, open 12 days. Risk score = 3 × 3 = 9, class Medium, and the deviation is not overdue.
Enter values above to see results.
High-risk deviations need a root-cause investigation and a corrective action before the affected work is repeated. Never close a deviation by changing the score — close it by fixing the cause. Tool 78 of 500 — GIFSQ
