# VCU STAT 210 - Exam 7 Study Guide (2 pages)

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## Exam 7 Study Guide

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An overview of the material presented in lecture in preparation of exam 7.

- Pages:
- 2
- Type:
- Study Guide
- School:
- Virginia Commonwealth University
- Course:
- Stat 210 - Basic Practice of Statistics

**Unformatted text preview:**

STAT 210 1nd Edition Exam 7 Study Guide Lectures 37 41 Lecture 37 November 19 Sampling Distribution of X 1 X 2 Statistical inferences involve the use of statistics calculated from sample data to make statements about population parameters that are unknown o Includes confidence intervals significance tests This chapter deals with making statistical inferences about the difference between two population means 1 2 Identify populations parameters then samples selected from the populations o Simple random sample of n1 from 1st population and simple random sample of n2 from second Then compute the sample means X 1 X 2 o The point estimate 1 2 is the difference in sample means o Samples can be selected independently or dependently of each other Assume the 2 samples are independent of one another in this chapter Possibility that n 1 and n2 won t be same Sampling distribution assumptions o Have 2 independent simple random samples o Either both populations normally distributed or both sample sizes are large enough for CLT to apply Know the formula for the sampling distribution for the difference in sample means Know z score transformation formula Keep in mind formulas given for exams Be able to recognize which formula to use when Go through examples from lecture and practice problems Lecture 38 November 21 Confidence Intervals for 1 2 Know sampling distribution assumptions same as for lecture 37 Because population means unknown must be estimated Confidence Interval for 1 2 Assumptions o Have 2 independent simple random samples o Either both populations normally distributed or populations large enough for CLT to apply o Population standard deviations 1 and 2 are known If assumptions satisfied 100 C confidence interval for 1 2 can be determined using the formula t table When 1 and 2 are unknown must use t statistic o Degrees of freedom equal to the smaller of n1 1 and n2 1 Go through examples from lecture and practice problems Lecture 39 November 24 Statistical Tests of 1 2 Tests of Significance for 1 2 o H 0 1 2 0 o H a 1 2 0 o H a 1 2 0 o H a 1 2 0 When standard deviations known use standard normal Z distribution when unknown use t distribution Decision conclusion determined the same as for all other tests Go through examples from lecture and practice problems Lecture 40 November 26 Statistical Tests of 1 2 Paired Data Suppose two samples are dependent or paired Tests of significance same Select srs of n subjects make 2 measurements on each subject for each subject in sample can compute difference between 2 measurements d X1 X2 this generates a sample of n differences d1 d2 dn Assumptions o SRS selected with 2 measurements on each subject o Differences are normally distributed or sample size is large enough for CLT to apply Paired t test is a regular t test with X d being the mean of the n differences and sd being the standard deviation of the n differences Go through examples from lecture and practice problems Lecture 41 December 1 Inferences for Comparing 2 Population Means This lecture just a wrap up of the previous lectures Go through examples from lecture and practice problems

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