Normal distribution vs Skewed distribution
How to tell Normal distribution and Skewed distribution apart when a board question makes them look alike.
Normal is symmetric with aligned center measures; skewed is asymmetric with mean pulled toward tail.
Side by side
Normal distribution is symmetric bell-shaped with mean, median, and mode aligned and standard deviation describing spread.
Skewed distribution is asymmetric with a tail pulling the mean toward the tail, often making median a better center measure.
Normal distribution is symmetric bell-shaped with mean, median, and mode aligned and standard deviation describing spread.
Skewed distribution is asymmetric with a tail pulling the mean toward the tail, often making median a better center measure.
The repair move
Before naming the answer, force the stem through the separator: Normal is symmetric with aligned center measures; skewed is asymmetric with mean pulled toward tail.
Try a free question
CoreA research study collects diastolic blood pressure measurements from 1,000 healthy adults. The data form a bell-shaped, symmetric distribution with mean 80 mmHg, median 80 mmHg, mode 80 mmHg, and standard deviation 10. Which type of distribution is this?
Show answer and explanation
Answer: A. Normal (Gaussian) distribution. Normal distribution (Gaussian) is symmetric and bell-shaped. Mean = median = mode. Empirical rule: 68% within 1 SD, 95% within 2 SDs, 99.7% within 3 SDs. Many biologic variables (height, blood pressure, IQ) are approximately normally distributed. Statistical tests assuming normality include t-tests, ANOVA, linear regression.
Why the other choices are tempting
- B. Right-skewed has long right tail with mean > median.
- C. Left-skewed has long left tail with mean < median.
- D. Bimodal has two peaks (might suggest two underlying populations).
- E. Uniform has equal frequency across values.
Flashcards
Tap a card to flip it.
What clue supports Normal distribution?
Choose Normal distribution when the stem gives this pattern: Normal distribution is symmetric bell-shaped with mean, median, and mode aligned and standard deviation describing spread.
What clue supports Skewed distribution?
Choose Skewed distribution when the stem gives this contrasting pattern: Skewed distribution is asymmetric with a tail pulling the mean toward the tail, often making median a better center measure.
Quick answers
What is the fastest way to tell Normal distribution from Skewed distribution?
Normal is symmetric with aligned center measures; skewed is asymmetric with mean pulled toward tail.
What is the key clue for Normal distribution?
Normal distribution is symmetric bell-shaped with mean, median, and mode aligned and standard deviation describing spread.
What is the key clue for Skewed distribution?
Skewed distribution is asymmetric with a tail pulling the mean toward the tail, often making median a better center measure.