Difference in means
Confidence intervals · Method and input reference
Independent observations. Mean and difference use t intervals (Welch for two groups); proportion uses Wilson; difference in proportions uses Newcombe; SD uses normal-population chi-square; correlation uses Fisher z. Synthetic example: Two independent blood-pressure cohorts: 120 and 96 people, with unequal variability; values in mmHg.
Open calculator · Compare methods in the decision matrix
When to consider it
- Estimate a difference between two independent means with a Welch interval.
Assumptions and scope
- Observations must be independent between subjects; repeated rows from one subject are not independent samples.
- Use the outcome and predictor coding required by the calculator; review missing data and model diagnostics.
Required inputs
- Observations — Numeric observations; preserve the row and column structure described above.
- Second sample — Numeric observations; preserve the row and column structure described above.
- Confidence level — Enter the method parameter described above.
Review missing values and data coding before running. Sample inputs are synthetic teaching examples.
Implementation
Lifescio implements the method-specific formula using the listed SciPy distribution functions and NumPy array arithmetic. See method help for assumptions.
- scipy 1.15.3: scipy.stats.t.ppf
These are pinned library versions; saved results record the versions actually used at runtime.