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: The degree of consistency in repeated measurements (low variability).
- Bias: The systematic deviation of the average measurement from the actual true value.
Step 2: Analysis of Instrument A.
Instrument A displays measurements that are widely dispersed around the true value. It exhibits neither precision nor unbiasedness. Therefore, statement (A) is erroneous.
Step 3: Analysis of Instrument B.
The measurements from Instrument B are closely grouped, indicating high precision. However, they are consistently higher than the true level, signifying a positive bias. Consequently, statements (B) and (C) are accurate.
Step 4: Analysis of Instrument C.
Instrument C produces scattered measurements, yet they are shifted above the true level, demonstrating a positive bias. It is not unbiased. Therefore, statement (D) is correct, and statement (E) is incorrect.
Step 5: Summary of Findings.
The accurate conclusions are limited to statements B, C, and D.