Lesson 1- COMM 215 Fall 2013 -Student Version


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Unformatted text preview: 4 ­year ­old as 42 year ­old –  Asking ambiguous ques1ons –  Inconsistency –  Spotng outliers –  Selec1on bias Descrip1ve Sta1s1cs •  DescripBve StaBsBcs u1lizes numerical graphical methods –  to look for paherns in a data set –  to summarize the informa1on revealed in a data set –  to present the informa1on in a convenient form. Sta1s1cal Inference •  InferenBal StaBsBcs u1lizes sample data –  to make es1mates, decisions, predic1ons, or other generaliza1ons about a larger set of data. Sample of 500 Students in COMM215 Year COMM215 Failure Rate 2009 12.7% 2010 12.3% 2011 12.1% 2012 ???? Ethical Guidelines for Sta1s1cal Prac1ce •  Sta1s1cal thinking –  Know how the data was collected ­ Is the data from a reliable source? –  Is it a random sample? Or “Self ­Selected”? –  Is it possible? Does the data make sense? •  If the biased sample was inten1onal, with the sole purpose to mislead the public the researchers would be guilty of unethical staBsBcal pracBce. Misleading Sta1s1cs •  “ Research Study Reveals…” As a sta1s1cs student who wishes to avoid accep1ng biased results, what single ques1on should be foremost in your mind as you begin reading the ar1cle? •  You should ask yourself what benefits the person or company stands to gain from the conclusions reached by the study. Misleading Sta1s1cs •  Forensic DNA Databases and Race: Issues, Abuses and Ac6ons held June 19 ­20, 2008, at New York University. To link to this paper, visit www.gene ­watch.org. Misleading Sta1s1cs 'One in several billion.' 'Oh, about 1 in 100.' 'Assuming that the defendant did not commit this crime, what is the probability that the defendant and the culprit having iden1cal fingerprints?' 'Let me ask you a different ques1on. What is the probability that a fingerprint lixed from a crime scene would be wrongly iden1fied as belonging to someone who wasn't there?' Misleading Sta1s1cs •  It's all about the ques1on asked. •  The defendant's fingerprints had been incorrectly iden1fied as being the same as the ones lixed from the scene. •  It is not a fact, it is a science, and is governed by probabili1es. References •  Sta1s1cs for Business and Economics •  Keller, G. (2012). Sta$s$cs for management and economics. Mason: Cengage Learning. •  McClave, J. T., Benson, G. P., & Sincich, T. (2008). Sta$s$cs for Business and Economics. New Jersey: Pren1ce Hall. •  Weirs, R. M. (2011). Introduc$on to Business Sta$s$cs. Mason: Cengage Learning....
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