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## z tests for percentages
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This test can be used if:
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- The data is a simple random sample from the population of interest
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- The sample size is large
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- A qualitative variable of interest summarized by percentages
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- Can use a box with tickets of 1s and zeros to represent the population
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If an observed value is too many SEs away from the expected value, it is hard to explain by chance.
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### Null Hypotheses
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| Term | Description |
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| ---- | ---- |
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| Null Hypothesis | This is a statement about a *parameter* |
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| Alternative/Research Hypothesis | What the researcher is out to prove, a statement of inequality. (Less than, greater than, not equal to). |
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| One-tailed test | Use when the alternative hypothesis says that the % of 1s is less than or greater than expected. It's one sided |
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| Two tailed test | When something is not equal to the expected. |
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## P Value
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The chance of observing at least a sample statistic, or something more extreme, if the null hypothesis is true.
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If the p-value is less than 5%, reject the null hypothesis.
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If the p-value is greater than 5%, fail to reject the null hypothesis.
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