GIFSQ Tools · Module 3 — Food Microbiology & Enumeration · Tool 058 of 500
Trend a run of environmental monitoring results: mean, maximum, share over the alert limit, and the direction of the trend.
Try sample values — fills the form with the worked example below.
Saved on this device only. Trend summaries are stored in this browser; they are not sent anywhere.
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Mean
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Maximum
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Over limit (%)
Trend slope: — per sample (least-squares line through the results in order).
Equation: Mean = sum ÷ n; over-limit % = 100 × (results above the limit ÷ n); slope = Σ(x - x mean)(y - y mean) ÷ Σ(x − x̄)², with x the sample order.
Method: Environmental monitoring trending per ISO 14644 and ISO 18593:2018 surface-sampling practice, with alert/action limits set in the site environmental monitoring programme; FDA guidance on aseptic processing expects trending of monitoring data.
Assumptions: Results are in time order, all from the same location and method, and the limit is the site alert limit for that location.
Limitations: A slope from few points is weak evidence — a run of rising points still needs an investigation, not a verdict from this tool alone.
Rounding: Mean and slope to 2 decimal places; over-limit % to 1 decimal place; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Environmental monitoring trending per ISO 14644 and ISO 18593:2018 surface-sampling practice, with alert/action limits set in the site environmental monitoring programme; FDA guidance on aseptic processing expects trending of monitoring data.
Assumptions: Results are in time order, all from the same location and method, and the limit is the site alert limit for that location.
Limitations: A slope from few points is weak evidence — a run of rising points still needs an investigation, not a verdict from this tool alone.
Rounding: Mean and slope to 2 decimal places; over-limit % to 1 decimal place; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: Results 10, 20, 30 against an alert limit of 25: mean 20.00, maximum 30, over limit 33.3%, slope +10.00 per sample — rising trend.
Saved trends
| Location | Mean | Max | Over limit (%) | Slope / sample |
|---|---|---|---|---|
| No trends saved yet. | ||||
Enter values above to see results.
Compare like with like — same location, same method, same limit — or the trend will mislead. Tool 058 of 500 — GIFSQ
