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For more information, please see full course syllabus of Statistics

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 2 answersLast reply by: Sarawut ChaiyadechSun Sep 8, 2013 3:22 AMPost by jerry yuan on August 26, 2011bro variance =/ sits s^2 come on

### Confidence Intervals for a Difference in Means

• If both independent sample are large or both populations from which the sample is selected are drawn from a normal distributions with known standard deviations, use the normal distribution to estimate μ1μ2.

• If both independent sample are large or both populations from which the sample is selected are drawn from a normal distributions with unknown standard deviations, use the t-distribution with ν = n1 + n2− 2 degrees of freedom to estimate μ1μ2 .

• If the sample size is large or the population of paired differences is normally distributed with unknown standard deviations, then use the t-distribution with ν = n− 1 degrees of freedom to estimate μd .

### Confidence Intervals for a Difference in Means

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

• Intro 0:00
• Independent Samples: Standard Deviations Known 0:07
• Confidence Interval for Difference of Means 1:12
• Example 1: Starting Salary 1:35
• Example 2: Fill 5:36
• Independent Samples: Standard Deviations Not Known 7:54
• Pooled Standard Deviation for Two Samples 8:46
• Confidence Interval for Difference of Means 9:32
• Example 3: Caffeine 10:35
• Example 4: Test Scores 15:20
• Inference about Difference of Means for Paired Samples 19:05
• Paired or Matched Sample
• Inference about Difference of Means for Paired Samples 20:58
• Extra Example 1
• Extra Example 2