Estimating precision for a multi-site study

Estimate the precision of the measurement procedure at multiple sites and samples.

1. Open the file tutorials\EP05-A3 Appendix B.xlsx.

   The worksheet opens showing 4 columns. The Sample column identifies the levels of the analyte in the sample (6 levels). Laboratory identifies the site (3 laboratories), Run identifies the run (5 runs per site). CA19-9 (kU/L) identifies the measured value for 5 replicates of sample in each run.

2. Click a cell in the dataset.
3. On the Analyse-it ribbon tab, in the Statistical Analyses group, click Precision, and then click 2 Factor Nested.
   The analysis task pane opens.
4. In the Y drop-down list, select Glucose.
5. In the Factor A drop-down list, select Day.
6. In the Factor B nested within Factor A drop-down list, select Run.
7. In the By drop-down list, select Sample.
8. In the Estimator drop-down list, select SD.
9. In the Confidence Interval edit box, type 95%, and then in the Method drop-down list, select Exact / Satterthwaite.
10. In the Conditions drop-down list, select Reproducibility / Repeatability to label the innermost variance component repeatability and the outermost reproducibility.
11. On the Analyse-it ribbon tab, in the MSA group, click Variability plot.
12. On the Analyse-it ribbon tab, in the MSA group, click Identify Outliers, and then on the analysis task panel in the Granularity drop-down list, select Level, Factor A so that outliers are detected for each sample and laboratory.
13. Click Calculate.

    The analysis report opens.