Q & A: The Rong Regulation, Turkey Mis-Totaling Total Error

Posted by Sten Westgard, MS

Often we get questions about the problems that laboratories encounter when they wrestle with their local regulations.

Here we have a case where there are Turkish laboratory regulations that are irrational. In the words of the submitter:

"I have a question about the estimation of total CV. We have a requlation about total allowable error in Turkey....It is Turkish, but I strongly believe that you can follow it.

"The marked page can be seen below: There is an example for glucose. Two levels of controls are measured and the CV%’s calculated. The total CV are calculated from the CV’s of two different levels as seen in the equation. I can not accept it, because the levels are different even if the CV’s are close."

What's gone Rong here? More after the jump...

The Turkish regulations is taking the two control levels of imprecision and adding the sum of their squares, then taking the square root. That result will be larger than is appropriate.

A simple average of the two levels of imprecision is more appropriate.

The square root of the summed squares would be appropriate if these were uncertainties to be combined, but this is performance at two separate levels. There's no reason to combine them this way.

Even better would be to select a specific level of the test as most important, as we do in the Sigma VP program, and just take the CV from that level.

The impact of this Rong Regulation is that it will increase the number of labs failing to me the Total Error goals. We hope that a change can be made to clear this up.

Have you been the victim of a Rong Regulation? Let us know, maybe we can help.