Why Use 50 Percent As The Expected Proportion?

When the proportion is unknown, 50 percent produces the most conservative variance and largest sample.

Sample Size Calculator

Estimate completed responses for a proportion with confidence, precision and finite-population correction.

Study Assumptions

Change a value to update the calculation.

Confidence LevelMargin Of Error%Expected Proportion%Finite Population (Optional)

Required Completed Responses

1,068

Unlimited-Population Size: 1,068
Critical z: 1.959964
Finite Population: Not applied

This is the simple-random-sample proportion formula. Increase the target for expected nonresponse, design effects, subgroup analysis and incomplete records.

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What Is the Sample Size Calculator?

The Sample Size Calculator estimates the completed simple-random-sample responses needed for a proportion and optionally applies finite-population correction.

How It Works

Set confidence, margin of error and expected proportion. Enter a known population only when sampling without replacement from that bounded group.

When to Use It

Use it for initial survey planning before allowances for nonresponse, design effects and subgroup reporting.

Frequently Asked Questions

Why Use 50 Percent As The Expected Proportion?: When the proportion is unknown, 50 percent produces the most conservative variance and largest sample.

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