Estimating the detection limit of a measurement system using a precision profile

Estimate the limit of detection of a measurement system or procedure using a precision profile variance function.

You must have already completed the task:
  1. Activate the analysis report worksheet.
  2. On the Analyse-it ribbon tab, in the MSA group, click Detection Capability.
    The analysis task pane Detection Capability panel opens.
  3. In the LoB Estimator drop-down list, select:
    Option Description
    Normal quantile Estimate the LoB using the 5% upper of the distribution of blank values (levels with assigned value 0).

    Use when values are normally distributed and not truncated at 0.

    Quantile Estimate the LoB using the 95th percentile of the distribution of blank values.

    Use when values are truncated at zero.

    Known value Use specific value as the LoB.
  4. If you selected Normal quantile, in the SD drop-down list, select:
    Option Description
    Blank material Estimate based on material assigned a value of 0.
    Precision profile at blank material value Estimate based on the precision profile variance function at the mean value of the material assigned a value of 0.
    Precision profile at zero Estimate based on the precision profile variance function at the value 0.

    Use when it is not possible to obtain blank material, but the profile function is representative of values near zero.

  5. In the Alpha edit box, type the probability that a blank material gives a result greater than the critical value (LoB), when in fact the substance is not present (typically 5%).
  6. In the SD drop-down list, select Precision profile function.
  7. In the Beta edit box, type the probability that a non-blank material gives a result less than the critical value (LoB) when in fact the substance is present (typically 5%).
  8. Click Calculate.