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Student’s Name Instructor’s Name Course Date Z-test and independent t-test: assumptions theory and calculations Question 1 90 percent confidence n1 = 11 n2= 18 x 1 = 744 x 2 = 299 σ21 = 62 σ22 = 32 Since the variance is known the 1001-α percent confidence interval for μ1-μ2 is given by ( x 1 - x2 )± z(1-α2)√( σ21)/ n1 + (σ22/ n2) ( x 1 - x2 ) = 744 – 299 = 445 √( 62/18) + (32/11) = 2.521 445± 1.645(2.521) (440.9 449.1) The difference between the two population (lean and obese) means is 445 and the researchers are 90% confident that the true mean lies between 440.9 and 449.1. 95 two populations are equal the point of estimate is given by ( x 1 - x2 ) = 20.6 – 17.4= 3.2 The pooled estimate of the variance is given by σ2 P ={(n1-1)σ21+(n2-1) σ22}/(n1+n2-2) σ2 P ={185-15.8+(86-1) 5.8}/(185+86-2) σ2 P=(18433.64+85(33.64))/270σ2 P = 33.52 The standard error is given by (33.52186+33.5286) = The 99% confidence interval is then given as 3.2±t(1.960) (33.52186+33.5286) 3.2±2.576(0.755) (1.3 5.1) The correct value of t to use for a 95% confidence interval with 270 degrees of freedom is 2.576. We interpret this interval that the difference between the two population means is estimated to be 3.2 and we are 99% confident that the true value lies between 1.3 and 5.1 [...]

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Please follow directions outlined in "1 Week 5 assignment document". In order to complete the assignment, you will need the "SPSS criminal record file". Please try to download from this link since it won't allow me to attach it here (please let me know if your unable to download it): https://drive.google.com/file/d/0B8bM7OwZexyuY3pscG9RWTkxdE0/view?usp=sharing

Subject Area: Statistics

Document Type: Dissertation Proposal