DA0-002 Data Analysis Practice Question
A data analyst is comparing the means of two independent groups using a t-test. The sample sizes are small and the data is not normally distributed. Which condition is violated for a valid t-test?
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
✓
Normality
The t-test assumes normality of the data, especially with small samples. Violation of normality can affect the validity.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Normality
Why this is correct
Normality is an assumption of t-test.
- ✗
Equal variances
Why it's wrong here
Even if variances unequal, Welch's t-test can be used.
- ✗
Independence of observations
Why it's wrong here
Independence might still hold.
- ✗
Sample size larger than 30
Why it's wrong here
Not an assumption; t-test can be used with small samples if normality holds.
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