Table of contents
- 1. Introduction to Statistics53m
- 2. Describing Data with Tables and Graphs2h 1m
- 3. Describing Data Numerically1h 48m
- 4. Probability2h 26m
- 5. Binomial Distribution & Discrete Random Variables2h 55m
- 6. Normal Distribution & Continuous Random Variables1h 48m
- 7. Sampling Distributions & Confidence Intervals: Mean1h 17m
- 8. Sampling Distributions & Confidence Intervals: Proportion1h 20m
- 9. Hypothesis Testing for One Sample1h 8m
- 10. Hypothesis Testing for Two Samples2h 8m
- 11. Correlation48m
- 12. Regression1h 4m
- 13. Chi-Square Tests & Goodness of Fit1h 30m
- 14. ANOVA1h 4m
7. Sampling Distributions & Confidence Intervals: Mean
Introduction to Confidence Intervals
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Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Find α for a 90% confidence interval.
A
α=0.90
B
α=0.10
C
α=0.05
D
α=0.01

1
Understand that the confidence level is the probability that the interval contains the true parameter value. For a 90% confidence interval, this means we are 90% confident that the interval contains the true parameter.
Recognize that the confidence level is related to the significance level, denoted as \( \alpha \). The significance level is the probability of rejecting the null hypothesis when it is true, which is the complement of the confidence level.
Calculate \( \alpha \) by subtracting the confidence level from 1. For a 90% confidence interval, \( \alpha = 1 - 0.90 \).
Perform the subtraction: \( \alpha = 0.10 \). This means that the significance level for a 90% confidence interval is 0.10.
Conclude that \( \alpha = 0.10 \) is the correct significance level for a 90% confidence interval, which corresponds to the probability of making a Type I error.
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