Statistics › Section J · Hypothesis testing with two samples › Topic J.1
Comparing two means with unknown spreads
Does the new method beat the old? Do two groups differ? Comparing two means is the most common question in applied statistics, and the machinery is familiar: the statistic becomes a difference, the standard error combines both samples' spreads, and the t distribution prices the comparison.
In this topic
- Two groups, one question
- The two-sample t statistic
- Why variances add
- Conditions: independent inside and out
- Worked example: two tutoring methods
- Worked example: the companion interval
- The interval-test agreement, again
- Common mistakes to avoid
- Key takeaways
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