Lecture 10 Chapter 9

# Lecture 10 Chapter 9 - Chapter 9 Introduction to the t...

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Click to edit Master subtitle style Chapter 9 Introduction to the t statistic

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The t Statistic The t statistic allows researchers to use sample data to test hypotheses about an unknown population mean. Advantage of the t statistic: does not require any knowledge of the population standard deviation. Is used to test hypotheses about a completely unknown population; that is, both μ and σ are unknown, and the only available information about the population comes from the sample.
The t Statistic (cont.) All that is required for a hypothesis test with t is a sample and a reasonable hypothesis about the population mean. There are two general situations where this type of hypothesis test is used:

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The t Statistic (cont.) 1. When a researcher wants to determine whether or not a treatment causes a change in a population mean. 2. To compare an actual sample mean with a hypothesized population mean. NOTE: when you know σ, compute a z-score, when you don’t, compute a t- statistic X – μ X – μ z = ──── t = ──── σ sM
The Estimated Standard Error and the t Statistic (cont.) The hypothesis test attempts to decide between the following two alternatives: 1. Is it reasonable that the discrepancy between M and μ is simply due to sampling error and not the result of a treatment effect? 2. Is the discrepancy between M and μ more than would be expected by sampling error alone? That is, is the sample mean significantly different from the population mean?

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## This note was uploaded on 03/11/2010 for the course PSYCH 211 taught by Professor Natalieperson during the Spring '10 term at Rhodes.

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Lecture 10 Chapter 9 - Chapter 9 Introduction to the t...

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