# Errors in estimation

**Please note:**

- You are inferring for a population, based only on a sample
- This is no proof that your decision is correct
- Itâ€™s just a hypothesis

- There is still a chance that your inference is wrong
- How do I quantify the prob. of error in inference?

- Type I and Type II Errors
- Type I error occurs if the null hypothesis is rejected when it is true
- Type II error occurs if the null hypothesis is not rejected when it is false

- Significance Level
- Î± -> Significance level
- the upper-bound probability of a Type I error

- 1 - Î± ->confidence level
- the complement of significance level

- Î± -> Significance level