Question

Fig. shows repeated glucose measurement for a single sample. Choose the correct findings from the following statements. 

LIST: 
A. Instrument A is precise and unbiased. 
B. Instrument B is precise and biased. 
C. Instrument B has a positive bias. 
D. Instrument C has only positive bias. 
E. Instrument C is unbiased. 
 

• A. B, C and D only
• B. A, D and E only
• C. A, B and C only
• D. B, C, D and E only

Hint:

Precision = closeness of repeated results. Bias = deviation from truth. Instrument B = precise but biased, Instrument C = biased only.

Answer 1

The Correct Option is A

Step 1: Define precision and bias.
- Precision: Consistency of repeated measurements (low variability).
- Bias: Deviation of the mean measurement from the true value.
Step 2: Instrument A.
Shows scattered values around the true level. Not precise, not unbiased. Hence statement (A) is incorrect.
Step 3: Instrument B.
Values are tightly clustered (precise), but consistently above the true level (positive bias). Hence statements (B) and (C) are correct.
Step 4: Instrument C.
Values are scattered, but shifted above the true level. It shows only positive bias but is not unbiased. Hence statement (D) is correct, (E) is incorrect.
Step 5: Conclusion.
Correct findings are B, C, and D only.