Lec38 - 13%)} __~ ” f 5 —W7t' PA VLZ: X- "RIM;...

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 2
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 4
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 6
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 8
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Background image of page 10
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 13%)} __~ ” f 5 —W7t' PA VLZ: X- "RIM; 4»! < X 4’ gym/— S" . “7‘ 1/; M C515 /_ 5 S .. + “m- [wq ,— x, ,m A MFflj/Yagilfiiflfl. M l C2D M,” >—. ' 5 a ’1 15 V5 Wmfiw M’s» b) TES$SW§ 1') 3570 J, 5p,“ Rm? V3 Tbfi+§W$183fi01 W301! (‘7; c) {W‘Qxh/IW weld VS W 60¢th (7%} A) SWWufaofiMLM-v Wfivwmk‘s CX’; Vs W WLW‘35 e) San/@455 900M .‘n S‘I’Evv) WWWLQFQM ye. 3W,e§ m. 83‘?ij MW ‘92 M.>/qz 17¢ Cf LAM <— Cowxfl, M LIV/Q] as car %2 Mr-Ab“ Example: Cholesterol levels. The cholesterol levels of a control group were measured and it was found that the mean level was 193. Levels on 28 heart attack patients 2 days after the attack were measured: 270 236 210 142 280 272 160 220 226 242 186 266 206 318 294 282 234 224 276 282 360 310 280 278 288 288 244 236 Question: Is the mean of this group different from 193? (Probably) First issue: How normal is the data? Frequency Histogram of chol 12 10 N - O - 100 150 200 250 chd 300 350 400 Normal Q-Q Plot Sample Quantiles 200 250 300 350 150 Theoretical Quantiles > t.test(chol,aIternative="two.sided",mu=1 93) One Sample t-test data: chol t = 6.7575, df = 27, p-value = 2.953e-07 95 percent CI: [235.4284, 272.4288] sample estimates: mean of x: 253.9286 36’. 7 Default confidence level is .95 but easy to change: t.test(chol,alternative="two.sided",mu=193, conf.level=.99) One Sample t-test data: chol t = 6.7575, df = 27, p-value = 2.953e-07 99 percent confidence interval: [228.9469, 278.9103] Note: If you want to be more confident (alpha=.1, 1-alpha=.99) you get a wider interval. Op NoOp 2.6 1.2 2.0 1.8 1.7 1.8 2.7 2.3 2.5 1.3 2.6 3.0 2.5 2.2 3.0 1.3 1.5 1.6 1.3 1.5 2.7 2.0 3637 Example: Parkinson’s Among other things Parkinson’s disease affects the ability to speak. In a study on Parkinson’s, eight of the afficted people received a common operation to treat the disease. This procedure seems to improve overall condition but does it improve ability to speak? Patients were given several tests to measure problems with speaking and the higher the score, the more problems with speaking. Results are summarized below where “Op=operation” and “NoOp=no operation performed”. The NoOp numbers leave us with a feeling of more small values so it is not clear the operation has a beneficial effect. We make a CI on differences of means to test for the significant difference. t.test(op,noop,alternative="two.sided",mu=0) data: op and noop t = 3.025, p-value = 0.007132 95 percent confidence interval: [0.1927797, 1.0643632] sample estimates: mean of x mean of y 2.450000 1.821429 Remarks: - The 95% CI for mu_op —mu_noop is [0.19, 1.06] and with 95% confidence one believes that mu_op>mu_noop. ° The means are not equal and there is a definite difference between the 2 populations of op and noop. The noOP patients have better scores for speaking ability. ...
View Full Document

Page1 / 10

Lec38 - 13%)} __~ ” f 5 —W7t' PA VLZ: X- &amp;quot;RIM;...

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online