Ch8_Z&T tests

Ch8_Z&T tests - Chapter 8 Introduction to...

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Chapter 8 Introduction to Statistical Hypothesis Testing : Z – test and One sample t – test
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Statistics are used to: Organize and describe data (Descriptive Statistics) Estimate the population parameter (Inferential Statistics) Test hypotheses based on Inferential Statistics. A statistical testing is a set of rules whereby a decision about the hypothesis is reached.
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Two Types of Test There are two types of statistical hypothesis test: Parametric Test Parametric tests often assume certain conditions (or distribution) for the scores in the population. Nonparametric Test No assumptions about the distribution of scores in the population. They are commonly known as distribution-free tests .
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Parametric test A statistical test involving hypotheses that makes statement about a population parameter (e.g. population mean, μ , or population variance, σ 2 ). Parametric tests require measurements to have interval or ratio scales. Parametric tests have specific assumptions about the population.
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Nonparametric Tests - Distribution-free Tests A statistical test involving hypotheses that do not make statement about a population parameter. Nonparametric tests can also be used for nominal or ordinal level data. These tests make no assumptions about the distribution of scores in a population.
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Statistical Hypotheses Hypothesis testing starts with a statistical hypothesis. For parametric tests, statistical hypothesis is a statement about a population parameter which may or may not true. For nonparametric tests, statistical hypothesis does not involve parameter. The observed distribution fits that expected. The two variables A and B are independent .
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Statistical Hypotheses Null Hypothesis : A statement of a condition assumed to be true about a population. We test the null hypothesis by a statistical test. We set up a hypothesis that is directly counter (opposite) to what we hope to show. Alternative hypothesis : A statement of what must be true if the null hypothesis is false.
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What Is a Null Hypothesis (H 0 ) in Parametric Tests A statistically testable hypothesis usually assumes something about the populuation parameter. Statistical criteria are used to determine if
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Ch8_Z&T tests - Chapter 8 Introduction to...

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