A Levey-Jennings chart shows control values gradually increasing over ten consecutive days. What is the most likely cause?
1Progressive reagent or calibrator deterioration✓ 정답
2Random error from pipetting
3A single clerical transcription error
4Normal statistical variation requiring no action
해설
A gradual movement in one direction over successive days is a trend, typically caused by progressive deterioration of reagent or calibrator. An abrupt change to a new level is a shift, commonly following a reagent lot change or instrument maintenance. The two patterns have different causes.