🧮 sample size calculator
⚡ determine the minimum number of participants for reliable studies — used by researchers & students
🔧 study parameters
choose the kind of data you measure
typical variability, e.g., from pilot or literature
1 means equal groups
📌 design effect (preview):
two‑independent‑means, two‑tailed
📋 required sample size
128
64 per group
two‑sample t‑test
- total participants: 128
- group A (control): 64
- group B (treatment): 64
- effect size (Cohen’s d): 0.5
- margin of error (est.)*: ±5.5%
🧾 interpretation
With 80% power and α=0.05, you need 64 subjects per group to detect a mean difference of 5 (SD 10).
⚠️ based on two‑tailed test, equal variances assumed. adjust for dropout.
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