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 0 answersPost by Jethro Buber on September 20, 2014Good question. I am puzzled about this too. 0 answersPost by Alex Moon on March 22, 2013how did he get d bar and Sd for example 5?

### Test for a Difference Between Two 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 test 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 test 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 test μd.

### Test for a Difference Between Two 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
• Standard Deviation Known, Unpaired 0:08
• Example 1: Boredom 1:17
• Example 2: Smoking 4:15
• Population Standard Deviations Unknown, But Equal 7:10
• Pooled Standard Deviation for Two Samples
• Example 3: Diet Soda 8:28
• Example 4: TV 12:12
• Paired Samples 15:50
• Example 5: Hormone Level 16:33
• Example 6: Hypnotism 19:43