Confidence intervals and margin error

Confidence intervals and margin error

1. 1. Determine population proportion

   • If not possible, we calculate a statistic to estimate the parameter

2. 2. Determine sample distribution for sample proportions

   • Usually X~iid Normal(p,σ²)

3. 3. Confidence interval defined as:

   • • Where α is usually 5%

4. 4. If we don't have σ, we use the following estimator:

   • • Which is an unbiased estimator

5. 5. Marginal error = Twice standard error

   • The more data (n) the less the marginal error

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