ENGR201_Fall2011_Lecture3

ENGR201_Fall2011_Lecture3 - ENGR 201 Evaluation &...

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1 4 October 2011 ENGR201 Lecture 3 Fall 2011 1 ENGR 201 Evaluation & Presentation of Experimental Data Lecture 3: Statistical Measurement Theory part 2 D. Miller, Mechanical Engineering & Mechanics Drexel University 4 October 2011 ENGR201 Lecture 3 Fall 2011 2 Quiz 1 Performance
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2 4 October 2011 ENGR201 Lecture 3 Fall 2011 3 Announcements Quiz 2 will be on-line Thursday 10/6 at 5:00 PM thru Friday 10/7 at 5:00 PM – Check BbVista for additional details Midterm is Thursday 10/13/2011Week 4 – Covers Chapter 1 and 4, labs 1 and 2 – 8:00-9:00 AM main auditorium written part (partial credit) • Calculators are permitted • Closed book and closed notes • One handwritten formula sheet permitted – On line component (no partial credit) 10/13 from 5:00 PM thru 10/14 5:00 PM 4 October 2011 ENGR201 Lecture 3 Fall 2011 4 Homework and Reading Week 3 Read textbook sections 4.4, 4.5, 4.7,4.8 make sure to pay attention to examples 4.4, 4.5, 4.6, 4.12, 4.13 and Table 4.7 on page 152 Problems from text: 4.11 (only analyze column 1), 4.12 (only analyze column 1), 4.26, 4.34, 4.42 Additional information to support lecture concepts Video: Statistics: Standard Deviation ( cut and paste link ) – Compare Student‟s t-distribution to normal distribution http://www-stat.stanford.edu/~naras/jsm/TDensity/TDensity.html – Effect of sample size on finite statistics Finite-population.vi in student area of textbook web site
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3 4 October 2011 ENGR201 Lecture 3 Fall 2011 5 Recap of Lecture 2 Gaussian or Normal Distribution Infinite statistics Defined by: mean, x‟ and variance, σ 2 . Probability P(x) that a variable x will fall within x‟ ± δx is the area under curve Interval with probability P(x‟-σ≤ x ≤ x‟+ σ) = 68.27% P(x‟-2σ≤ x ≤ x‟+ 2σ) = 95.45% P(x‟-3σ≤ x ≤ x‟+ 3σ) = 99.73% P x ' x x x ' x p x   dx x ' x x ' x 4 October 2011 ENGR201 Lecture 3 Fall 2011 6 Back to original question from Lecture 2 We measure the diameter of 10 parts (sample) from a population in a crate and find the average, We want to know how well the average diameter of our small sample represents the true average diameter, x‟, of the entire crate! Estimate true value x‟ as: x ' x u x P % x ±μ x is the uncertainty interval in the estimate at some probability level
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4 4 October 2011 ENGR201 Lecture 3 Fall 2011 7 Today‟s Topics will answer that question and more • Since you can rarely measure every item in a population • If you measure just part of the population (a sample), what can we say about the population as a whole? Central Tendency
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This note was uploaded on 10/07/2011 for the course ENGR 201 taught by Professor Miller during the Fall '08 term at Drexel.

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ENGR201_Fall2011_Lecture3 - ENGR 201 Evaluation &...

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