This is page twenty-two of the series of free video lessons, "Statistics Lectures".

### Statistics - Lecture 66

Confidence Intervals for Dependent Samples t-Test

We use the Dependent Samples t-Test to test if two sample menas are different from one another.

After the t-Test, confidence intervals can then be constructed to estimate how large that mean difference is.

### Statistics - Lecture 67

Effect Size for Dependent Samples t-Test

The effect size allows us to measure the magnitude of mean differences.

This is usually calculated after rejecting the null hypothesis in a statistical test. If the null hypothesis is not rejected, effect size has little meaning.

### Statistics - Lecture 68

z-Test for Proportions, Two Samples

Researchers want to test the effectiveness of a new anti-anxiety medication. In clinical testing, 64 out of 200 people taking the medication report symptoms of anxiety. Of the people receiving a placebo, 92 out of 200 report symptoms of anxiety. Is the medication working any differently than the placebo? Test this clain using alpha = 0.05

1. Define Null and Alternative Hypotheses

2. State Alpha

3. State Decision Rule

4. Calculate Test Statistic

5. State Results

6. State Conclusion

### Statistics - Lecture 69

Confidence Intervals for the Difference of Two Proportions

We use the z-Test for Proportions to test if two proportions are different from one another.

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