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# Strategies When Population Distributions are Not Normal: Data Transformations and Rank-Order Tests - PowerPoint PPT Presentation

Chapter 15. Strategies When Population Distributions are Not Normal: Data Transformations and Rank-Order Tests. Assumptions in the Standard Hypothesis-Testing Procedures. Populations follow a normal curve Populations have equal variances Ceiling and floor effects. Data Transformations.

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## PowerPoint Slideshow about 'Strategies When Population Distributions are Not Normal: Data Transformations and Rank-Order Tests' - skipper

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Presentation Transcript

Strategies When Population Distributions are Not Normal:

Data Transformations and

Rank-Order Tests

• Populations follow a normal curve

• Populations have equal variances

• Ceiling and floor effects

• Data transformation

• Square-root transformation

• Legitimacy of data transformations

• Kinds of data transformations

• Square root transformation

• Log transformation

• Inverse transformation

• Arcsine transformation

• Rank-order transformation

• Rank-order tests

• Nonparametric tests

• Parametric tests

• Basic logic

• The null hypothesis

• Normal curve approximations

• Using parametric tests with rank-transformed data

• Relative risk of Type I and Type II errors

Controversies and Recent Development

• Computer-intensive methods

• Randomization tests

• Proposed alternative to parametric and nonparametric methods

• Widely applicable

• Unfamiliar to researchers

• Data transformations

• Described just prior to analyses using them

• Rank-order methods

• Described much like any other kind of hypothesis test