**Question:** A study was conducted on two different samples for comparing variation between DBP (diastolic blood pressure) and Vitamin D levels. Diastolic blood pressure normal is 110 with standard deviation 11 and vitamin D levels normal is 18 with standard deviation 3. Which of the samples has more variable?

**Core Concept:** The comparison of variability between two variables, DBP and Vitamin D levels, is based on the standard deviation (SD) values. In statistics, a higher SD indicates greater variability.

**Why the Correct Answer is Right:**

In this case, we compare the standard deviations of DBP (11) and Vitamin D levels (3). The standard deviation of Vitamin D levels (3) is lower than that of DBP (11). As a result, the variability in Vitamin D levels is lesser than that of DBP.

**Why Each Wrong Option is Incorrect:**

A. Vitamin D levels (18, SD 3) has a lower standard deviation compared to DBP (11, SD 11), making Vitamin D levels a less variable parameter.
B. DBP (11, SD 11) has a higher standard deviation than Vitamin D levels, further supporting the conclusion that Vitamin D levels are less variable.
C. This option is incorrect because the comparison is based on SD values, and Vitamin D levels have a lower SD value compared to DBP, making Vitamin D levels less variable.
D. The SD values for DBP and Vitamin D levels are compared, and Vitamin D levels have a lower SD value, indicating less variability.

**Clinical Pearl:**

Understanding variability helps in interpreting the clinical significance of the data. A lower standard deviation implies that the values are more dispersed around the mean, while a higher standard deviation signifies more dispersion of values around the mean. This concept is essential in evaluating the stability of measurements or interventions.

**Correct Answer:** Vitamin D levels (18, SD 3) have a lower standard deviation compared to DBP (11, SD 11), making Vitamin D levels less variable.