AWS Certified Machine Learning – SpecialtyExploratory Data AnalysisMedium
A data scientist is analyzing a dataset of customer purchase histories. They want to understand if there is a statistically significant difference in the average purchase amount between customers who used a promotional code and those who did not. The purchase amounts are normally distributed, and the sample sizes for both groups are large. Which statistical test should be used?
- AIndependent Samples t-test
- BPaired Samples t-test
- CANOVA
- DChi-squared Test of Independence
Show answer & explanationAnswer & explanation
Correct answer: A. Independent Samples t-test
An Independent Samples t-test is appropriate for comparing the means of two independent groups when the data is normally distributed and sample sizes are sufficiently large.
Why the other options are wrong
- B. Paired Samples t-test is used when the two groups are dependent or related (e.g., before and after measurements).
- C. ANOVA (Analysis of Variance) is used to compare means of three or more groups, not just two.
- D. Chi-squared Test of Independence is used for categorical variables, not for comparing means of continuous variables.
Independent Samples t-test
A statistical hypothesis test used to determine if there is a significant difference between the means of two independent groups on a continuous dependent variable.
- Compares means of exactly two groups.
- Groups must be independent.
- Dependent variable must be continuous and approximately normally distributed.
- Assumes equal variances (or uses Welch's t-test if not).
Memory trick: Two means, independent groups? T-test takes the lead!