DA0-002 Data Analysis Practice Question
During data exploration, an analyst notices that the target variable has a heavily right-skewed distribution. Which data transformation would be most appropriate to make the distribution more symmetric?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Log transformation
Log transformation is appropriate for heavily right-skewed distributions because it compresses the high values and spreads out the low values, making the distribution more symmetric. Square root transformation is better for moderate skew, and reciprocal transformation is for severe skew. Therefore, option A (Log transformation) is correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Log transformation
Why this is correct
Log transformation compresses the long right tail by rescaling values on a multiplicative scale, pulling extreme high observations closer to the bulk. This reduces positive skewness, making the target distribution more symmetric and better suited to techniques assuming normality.
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Reciprocal transformation
Why it's wrong here
The reciprocal transformation reverses order and is defined only for non-zero values, so it cannot symmetrise a right-skewed target containing zeros. It is tempting because it is a genuine power-family transform, but it is the right choice only for certain reciprocal-scale quantities, not general skew correction.
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No transformation needed
Why it's wrong here
Right-skewed data needs a log or square-root transform to compress the long right tail and approximate symmetry. Leaving the target untransformed preserves the skew, violating the normality assumption many models rely on. No transformation is only acceptable when the distribution is already roughly symmetric or the algorithm is distribution-agnostic.
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Square root transformation
Why it's wrong here
The square root compresses large values only mildly, so a heavily right-skewed target remains skewed after applying it. It is tempting because it is a legitimate variance-stabilising transform, but it is the right choice only for moderate skew, not the heavy skew described.
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This DA0-002 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the DA0-002 exam.