Background Threshold
statisticsUpper background limits: UCL, UPL, UTL and USL.
Data
One result per line. Columns can be separated by spaces, commas, semicolons or tabs, so you can paste straight from Excel.
| Column | What it is | Example |
|---|---|---|
| 1. Result | The measured background value | 12.4 |
A line looks like 12.4
For a result below the laboratory limit of reporting, enter it as <LOR, e.g. <0.5.
Drop a CSV or Excel file here, or
Read in your browser and put in the box below. The file itself is not uploaded.
10 value(s) parsed
Options
Paste your data and run the analysis
The chosen background limit and a histogram will appear here.
What this calculates
Upper background limits for an environmental dataset: the upper confidence limit of the mean (UCL, delegated to the 95% UCL engine), upper prediction limit (UPL) for k future observations, upper tolerance limit (UTL) covering a chosen proportion of the population, and upper simultaneous limit (USL) bounding all sample observations at once - with automatic or manual distribution selection and non-detect substitution.
Method references
US EPA statistical guidance for background comparisons (Singh and Nocerino) and Gilbert (1987) Statistical Methods for Environmental Pollution Monitoring.