One standard detion in normal standard curve includes value-
The question is asking what percentage of data falls within one standard deviation from the mean. From what I remember, in a normal distribution, about 68% of the data lies within ±1 standard deviation, 95% within ±2, and 99.7% within ±3. That's the empirical rule, also known as the 68-95-99.7 rule. So the correct answer here should be 68%.
Now, the user mentioned that the options A to D are missing. But since the correct answer is supposed to be one of them, I can infer that the options likely include 68%, 95%, 99.7%, and maybe a distractor like 50%. The incorrect options would be the other percentages. For example, if an option says 95%, that's two standard deviations, not one. Similarly, 99.7% is three. The 50% is probably a trick option.
I need to explain why each wrong option is incorrect. For Option A (if it's 95%), that's two SDs. Option B (if 99.7%) is three SDs. Option C (50%) is not part of the empirical rule. The clinical pearl here is to remember the 68-95-99.7 rule. It's high-yield for statistics in medical exams. Students might confuse the percentages with different standard deviations, so emphasizing the exact numbers is key.
**Core Concept**
The normal standard curve (Gaussian distribution) describes how data is distributed around the mean in a population. One standard deviation (SD) from the mean encompasses **68%** of the data in a normally distributed dataset. This is part of the **empirical rule** (68-95-99.7 rule), which is critical for interpreting statistical results in clinical research.
**Why the Correct Answer is Right**
In a normal distribution, **68% of values lie within ±1 SD** of the mean. This is a foundational statistical principle used to assess variability and probability. For example, if a lab test has a mean of 100 and SD of 15, 68% of results will fall between 85 and 115. This is mathematically derived from the integral of the normal distribution curve between -1σ and +1σ.
**Why Each Wrong Option is Incorrect**
**Option A:** Likely represents 50% (incorrect, as this is not a standard deviation boundary in normal distribution).
**Option B:** Likely represents 95% (incorrect, as this corresponds to ±2 SDs, not 1 SD).
**Option C:** Likely represents 99.7% (incorrect, as this corresponds to ±3 SDs, not 1 SD).
**Clinical Pearl / High-Yield Fact**
**Memorize the 68-95-99.7 rule**:
- 68%