Day 17: STA205 - Introduction to Statistical Methods

Today:

Return quiz on the sample proportion
- remember the extra step to test for normality of the sample proportion's distribution
Quiz 8: confidence intervals
- Z-table
- Important formulas
Extra credit opportunity
- Conduct a statistical study on a topic of interest (perhaps from your major?)
- Collect data and estimate a parameter or parameters
- Write a report
- potentially replacing an exam (provided it's better than an exam!)
#2, section 5.2 -- answer in back is wrong: should be .0749
For the following sections, you may want to refer to your Hypothesis testing handout
Section 7.2: Performing a test of hypothesis about
- We'll use a "Z-Test" (see p. 246) when conditions are appropriate (see p. 245).
- In these problems, the final step is interpretation. There are two guides to interpretation, on pages 252 and 254.
- Examples:
  - Example 7.5 (also given on the course website of worked examples -- interesting twist on the sample size...)
  - #2, p. 256
  - #5, p. 257

Section 7.3: Possible errors and level of significance

Alternative vocabulary: false positive, false negative....

The following table (thanks Wikipedia) illustrates the situation:

		Actual condition
		Present	Absent
Test result	Positive	Condition Present + Positive result = True Positive	Condition absent + Positive result = False Positive Type I error
Test result	Negative	Condition present + Negative result = False (invalid) Negative Type II error	Condition absent + Negative result = True (accurate) Negative

The probability of a Type I error is given by , the level of significance of the test.
Examples:
- #3, p. 265
- #4, p. 265

Links

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