The students in a psychology class seemed to think that the midterm exam was very easy. If they are correct, what is the most likely shape for the distribution of exam scores?

• A. Symmetrical
• B. Positively skewed
• C. Negatively skewed
• D. Normal

Answer: (C)

Skewness describes where the bulk of the scores lie and which direction the tails extend. If the exam is very easy, most students will score high, so the data pile up near the top end and the left side (low scores) trails off more slowly. That creates a longer tail on the left, or a negative (left) skew. A positively skewed distribution would have a longer tail to the right (toward higher scores), which would happen if the exam were hard and few people did well. A normal distribution would be symmetric, with tails of equal length on both sides.