Sample Size Calculator

Advanced EpiCalc

Study Designs

Advanced EpiCalc

Cross-Sectional Case-Control Cohort Study RCT & Variants Pre & Post Cluster Trial Field Trial

Cross-Sectional Study

Expected Prevalence

%

Margin of Error (Precision)

%

Confidence Level 90% 95% 99%

Expected Odds Ratio (OR)

Prevalence in Unexposed

%

Confidence Level (2-sided) 95% 99%

Statistical Power 80% 90%

Ratio (Unexposed:Exposed)

---

Design Effect (DEFF)

Total Sample Size

-

Exposed: | Unexposed:

Case-Control Study

Expected OR

Exposure in Controls

%

Confidence Level 95%99%

Power 80%90%

Ratio (Controls:Cases)

Design Effect (DEFF)

Cases

-

Controls

-

---

Total

-

Cohort Study

Expected RR

Incidence in Unexposed

%

Confidence Level 95%99%

Power 80%90%

Ratio (Unexposed:Exposed)

Design Effect (DEFF)

Exposed

-

Unexposed

-

---

Total

-

Randomized Control Trial (RCT)

Margin (δ)

The predefined margin of clinical significance.

Mean (Treatment) μ1

Mean (Control) μ2

Standard Deviation (SD)

Proportion (Treatment) p1

%

Proportion (Control) p2

%

---

Alpha (Significance) 5% (2-sided Z=1.96) 5% (1-sided Z=1.64)

Power 80%90%

Ratio (T:C)

Treatment Arm

-

Control Arm

-

---

Total Sample Size

-

Pre and Post Design (Paired)

Expected Mean Difference

Standard Deviation of Differences

Prop. Discordant (Success -> Fail)

%

Prop. Discordant (Fail -> Success)

%

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Confidence Level 95%99%

Power 80%90%

Pairs Required

-

Cluster Trial Adjustment

Base Sample Size (Unadjusted total N)

Calculate this in another tab (e.g., RCT) and enter here.

Intra-cluster Correlation Coefficient (ICC)

Average Cluster Size (m)

Design Effect (DEFF)

-

---

Total Adjusted Sample Size

-

Total Clusters Required

-

Field Trial (e.g., Vaccine Efficacy)

Expected Efficacy (VE)

%

Incidence (Attack Rate) in Controls

%

Confidence Level 95%99%

Power 80%90%

Ratio (Vaccinated:Control)

Design Effect (DEFF)

Vaccinated Required

-

Controls Required

-

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Total Sample Size

-