Sample Size Calculator for Comparing Two Independent Proportions

  • Provides live interpretations.
  • Assesses the influence of changing input values.
  • Adjusts sample sizes for continuity and clustering.

Input Values

Specify input values and click Calculate. Hover over for help.

  0.20

(Alternatively, specify a Measure of Association)

  0.35

Note: You may change the default options for Power, Significance, Alternate Hypothesis and Group Sizes by clicking the 'Options' button. You may also adjust the calculated sample size for continuity correction, clustering or response rate using the 'Adjust' button.


Influence of Changing Input values on Sample Size Estimates

Customize Visualisation

Customize the plot by changing input values from here.

From Min
To Max
By
(Select)
1st Series
2nd Series
3rd Series

Note: You may change the default options for Power, Significance, Alternate Hypothesis and Group Sizes by clicking the 'Options' button. You may also adjust the calculated sample size for continuity correction, clustering or response rate using the 'Adjust' button.

Visualisation

This is a plot of sample sizes for a range of expected proportions in the reference group and for three values of Effect Size. Customize the plot by changing input values from the 'Customize Visualisation' panel.

Download Figure

Table of Sample Sizes at a range of Expected Proportions.

Customize Table

Customize the table by changing input values from here.

From Min
To Max
By
From Min
To Max
By

Note: You may change the default options for Power, Significance, Alternate Hypothesis and Group Sizes by clicking the 'Options' button. You may also adjust the calculated sample size for continuity correction, clustering or response rate using the 'Adjust' button.

Sample Size Table

This table shows sample sizes for a range of expected proportions in the two groups. Customize the table by changing input values from the 'Customize Table' pane.

Download Table