The Control Values for Both Controls for the Prothrombin Test $\pm$

question 17

Multiple Choice

The control values for both controls for the prothrombin test were ranging between the mean and $\pm$ 1 SD for the first 19 days of use. Starting on day 20, the values for both were consistently between +1 and +2 SDs. This is an example of a:

• A) Shift
• B) Trend
• C) Random error
• D) Predictable error