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P Hat Calculator

Calculate sample proportion p-hat from the number of successes and sample size for polls, surveys, and inferential statistics.

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What Is p-hat?

The sample proportion $\hat{p}$ (p-hat) is the fraction of successes in a sample. It estimates the true population proportion from survey, poll, or experiment data. Related tools: Confidence Interval for Proportion Calculator and Sample Size Calculator.

p-hat Formula

Divide the number of successes $x$ by the sample size $n$.

$$\hat{p} = \frac{x}{n}$$

The standard error of the sample proportion is $\sqrt{\hat{p}(1-\hat{p})/n}$. This measures typical sampling variability when estimating a population proportion.

Example

In a poll of 700 students, 450 support a menu change. Then $\hat{p} = 450/700 \approx 0.643$, or about 64.3%.

Frequently Asked Questions

Can p-hat equal exactly 0 or 1?

Yes, if all sample observations are failures or all are successes. Both are valid sample proportions.

How is p-hat different from population proportion p?

p-hat is computed from a sample and varies from sample to sample. The population proportion p is the fixed true fraction in the entire population.

What if successes exceed sample size?

That is invalid input. Successes must be between 0 and the sample size inclusive.

Why report standard error?

Standard error shows how much p-hat might vary across repeated samples of the same size, which is essential for confidence intervals and hypothesis tests.