DA0-002 Data Analysis Practice Question
A data analyst is performing a chi-square test of independence on a contingency table of customer satisfaction (satisfied, neutral, dissatisfied) by region (North, South, East, West). Which THREE of the following are necessary assumptions for the test?
⚠ Common exam trap
The trap is importing parametric assumptions (normality, n > 30) from t-tests and ANOVA into chi-square, which is a non-parametric test concerned only with categorical counts and expected frequencies.
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
✓
The two variables are categorical
Option A is correct because the chi-square test of independence requires both variables to be categorical (nominal or ordinal), which holds here since satisfaction level and region are categorical variables. Option C is correct because the test relies on the chi-square approximation, which is valid when expected cell frequencies are sufficiently large—typically at least 5 in each cell, or in most cells (with no cell below 1) for larger tables. Option D is correct because each observation must be independent, meaning each respondent contributes to only one cell of the contingency table, with no repeated or paired measurements. Option B is incorrect because there is no fixed sample-size threshold of 30; adequacy is judged by expected frequencies, not raw n. Option E is incorrect because chi-square tests make no normality assumption—they operate on counts of categorical data, not continuous normally distributed variables.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The two variables are categorical
Why this is correct
Chi-square of independence compares observed against expected counts across categories, so both variables must be categorical. Satisfaction and region are nominal groupings, not continuous measurements; treating them as such would violate the test's foundation and invalidate the computed statistic.
- ✗
The sample size is greater than 30
Why it's wrong here
Chi-square requires expected frequencies of at least five in each cell, not a total sample exceeding 30. The threshold is tempting because n>30 underpins the central limit theorem for means-based parametric tests, but the chi-square statistic's distribution depends on cell-level expected counts, not overall sample size.
- ✓
Expected frequencies in each cell are at least 5 (or most cells)
Why this is correct
The chi-square approximation relies on adequate expected counts, conventionally at least 5 per cell, to avoid distorted p-values. With a 3x4 table, sparse cells would inflate Type I error, so pooling categories or using Fisher's exact test becomes necessary.
- ✓
The observations are independent
Why this is correct
Each respondent must contribute to exactly one cell, with no repeated or matched measurements, so cell counts behave as independent multinomial observations. Violating this inflates the chi-square statistic and produces falsely significant results about satisfaction and region.
- ✗
The data must be normally distributed
Why it's wrong here
Chi-square tests counts of categorical variables and assumes expected frequencies of at least five per cell, not normally distributed data. Normality is assumed by parametric tests such as t-tests or ANOVA on continuous variables, making it tempting here despite being irrelevant to contingency tables.
About these practice questions
One of 1,004 original DA0-002 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official CompTIA exam blueprint
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.