Table 2.
Summary of fitted intra- and inter-laboratory standard deviations obtained from the mixed models described in the text. Variance ratios indicate the relative size of the between-laboratory variation for each analyte (values above 1 show an improvement observed when using the common IS). The last column indicates whether observed improvements were significant; this was based on whether separate random effects were required for the two IS types. All standard deviations are shown in µmol/L.
| Inter Laboratory Standard Deviation | |||||
|---|---|---|---|---|---|
| Analyte | Common IS | In-House IS | Variance Ratio (in-House/Common IS) |
Intra-Laboratory Standard Deviation | Improvement Observed? |
| C10 | 0.175 | 0.252 | 2.07 | 0.403 | Yes |
| C5DC | 0.082 | 0.199 | 5.86 | 0.276 | Yes |
| C5 | 0.149 | 0.101 | 0.46 | 0.378 | No |
| Leucine | 0.040 | 0.098 | 5.93 | 0.246 | Yes |
| Methionine | 0.088 | 0.154 | 3.03 | 0.257 | Yes |
| C8 | 0.053 | 0.163 | 9.59 | 0.359 | Yes |
| Phenylalanine | 0.107 | 0.079 | 0.55 | 0.223 | No |
| Tyrosine | 0.162 | 0.125 | 0.59 | 0.382 | No |