Week9.pdf - Lecture 1 Two-Sample t-Test Slide 9.3 9.126 Week 9 Announcement The due date for the statistics assignment is Friday 15th(Week 9 November

# Week9.pdf - Lecture 1 Two-Sample t-Test Slide 9.3 9.126...

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Lecture 1: Two-Sample t -Test Slide 9.3 / 9.126 Week 9 Announcement The due date for the statistics assignment is Friday 15th (Week 9) November before 2pm. The link to submit your assignments on Moodle will be open soon. You can ask questions on the dedicated Moodle forum which is located in the assessment tab . Week 9 online tutorial is due Sunday before 6pm. Chapter 9 : Statistical Inference for Two Parameters MATH1041: Page 990 / 1115
Lecture 1: Two-Sample t -Test Slide 9.4 / 9.126 The Agenda Slide Overarching aim of the course: introducing Statistics, the study of collecting, analysing and interpreting data (fundamental to any quantitative research) First class of Week 9 Last time: Confidence intervals for a proportion Hypothesis tests for a proportion Today: Two-sample t -test Paired t -test For next time: Read appropriate pages in the textbook Chapter 9 : Statistical Inference for Two Parameters MATH1041: Page 991 / 1115
Lecture 1: Two-Sample t -Test Slide 9.5 / 9.126 Lecture 1 Learning Outcomes [ Ch9-L1-O1 ] Understand formulas for two-sample t -test [ Ch9-L1-O2 ] Know the formula for confidence intervals for the difference of means for independent samples By the end of this lecture you should be able to: Perform a two-sample t -test Build a confidence interval for a difference in means Chapter 9 : Statistical Inference for Two Parameters MATH1041: Page 992 / 1115
Lecture 1: Two-Sample t -Test Slide 9.6 / 9.126 Data analysis for one or two variables one variable two variables variable type: categorical quantitative both categorical one categorical, one quantitative both quantitative useful for inference: CI for p (for binary var) CI for μ CI for μ 1 - μ 2 CI for β 1 useful test: 1-samp for p (for binary var) 1-sample t - test for μ (or Z -test if σ known) χ 2 test for indepen- dence 2-sample t (for independence binary+quant) test regression slope ( β 1 ) Chapter 9 : Statistical Inference for Two Parameters MATH1041: Page 993 / 1115
Lecture 1: Two-Sample t -Test Slide 9.7 / 9.126 Example – Do Ravens Fly to Gunshots? Example 9.73 Do ravens intentionally fly towards gunshot sounds (to scavenge on the carcass they expect to find)? ( Ecology 2005, 86:1057–1060) Crow White addressed this question by counting raven numbers at a location, firing a gun, then counting raven numbers 10 minutes later. He did this in 12 locations. Results: location 1 2 3 4 5 6 7 8 9 10 11 12 before 1 0 1 0 0 0 0 5 1 1 2 0 after 2 3 2 2 1 1 2 2 4 2 0 3 Is there evidence that ravens fly towards the location of gunshots? Chapter 9 : Statistical Inference for Two Parameters MATH1041: Page 994 / 1115
Lecture 1: Two-Sample t -Test Slide 9.8 / 9.126 Example – Pregnancy and Smoking Example 9.74 What is the effect of a mother’s smoking during pregnancy on the resulting offspring? ( Journal of General Psychology 1993, 120(1): 49–63) A randomised controlled experiment investigated this by injecting pregnant guinea pigs with 0.5 mg/kg nicotine hydrogen tartrate in saline solution. The control group was injected with a saline solution without nicotine.

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