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BIOL 300: Biostatistics






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BIOL 300: Biostatistics BIOL 300: Biostatistics Presentation Transcript

  • BIOL 300: Biostatistics
  • Statistical quotations
    • There are three kinds of lies: lies, damn lies, and statistics.
      • Benjamin Disraeli / Mark Twain
  • Statistical quotations
    • There are three kinds of lies: lies, damn lies, and statistics.
      • Benjamin Disraeli / Mark Twain
    • It is easy to lie with statistics, but easier to lie without them.
      • Frederick Mosteller
  • Professor: Dr. Luke Harmon Department of Zoology Office: 1370 Biosciences Office Hours: 2 - 4 pm Mondays (or after class) e-mail: [email_address]
  • Course website
    • http://www.zoology.ubc.ca/~bio300/
    • Lecture notes
    • Textbook and Lab Manual
    • Assignments and answers
    • Contact information
  • Textbook
    • Whitlock and Schluter, The analysis of biological data
    • Available in two installments at CopieSmart, UBC Village
    • Also available online
  • JMP
    • Optional statistical software
    • Used in labs
    • Available in bookstore
    • 60-day trial version on web:
    • www.jmp.com
  • Evaluation
      • Final 50%
      • Mid-term 30%
      • Assignments (homework) 10%
      • Lab exam (final week of term) 10%
  • Examinations
    • Midterm: Thursday October 19 in class
    • Final exam: TBA
    • Old exams will be posted on the website
  • Assignments
    • Available on course web-page, announced in class
    • Due on Fridays at noon, at your TA’s office
    • (eight days after they are assigned)
    • Bonus points for in-class quizzes and activities
  • Lab
    • Begins third week of term
    • (September 18- 22)
    • Biol. Sci. room 2434
    • Lab exam during final week of classes
    • Book available at Copiesmart in the village and online
  • Class Forum
    • There will be a forum for discussion on the web
    • Discussion of lectures, labs, and homework
    • More details available next week
    • Credit given for only one of BIOL 300, FRST 231, STAT 200, PSYC 218 or 366.
    • These are paired with BIOL 300, but do not count as requirements for Biology majors and pre-reqs
  • Introduction to statistics
    • Statistics - technology used to describe and measure aspects of nature from samples
    • Statistics lets us quantify the uncertainty of these measures
  • http://www.pbs.org/wgbh/evolution/library/01/5/image_pop/l_015_04.html
  • http://www.rit.edu/~rhrsbi/GalapagosPages/DarwinFinch.html
  • The history of statistics has its roots in biology
  • Sir Francis Galton Inventor of fingerprints, study of heredity of quantitative traits Regression & correlation Also: efficacy of prayer, attractiveness as function of distance from London
  • Karl Pearson Polymath- Studied genetics Correlation coefficient  2 test Standard deviation
  • Sir Ronald Fisher The Genetical Theory of Natural Selection Founder of population genetics Analysis of variance likelihood P -value randomized experiments multiple regression etc., etc., etc.
  • Goals of statistics
    • Estimation
      • Infer an unknown quantity of a population using sample data
    • Hypothesis testing
      • Differences among groups
      • Relationships among variables
  • Statistics is also about good scientific practice
  • Introductory Puzzle
    • How to protect bombers flying over enemy territory?
    • British Air Ministry - WWII
    • Looked at distribution of bullet holes in airplanes returning from bombing runs
  • http://digitalroam.typepad.com/digital_roam/2006/03/the_hole_story_.html
  • Results
    • Where should more armor be added to the airplanes?
    • Explain your conclusion
  • Variable
    • A variable is a characteristic measured on individuals drawn from a population under study.
    • Data are measurements of one or more variables made on a collection of individuals.
  • Explanatory and response variables
    • We try to predict or explain a response variable from an explanatory variable.
  • Mortality on the Titanic , as predicted by sex
  • Populations and samples
  • P opulations <-> P arameters; S amples <-> E s timates
  • Nomenclature s  Standard Deviation s 2   Variance  Mean Sample Statistics Population Parameters
  • Properties of a good sample
    • Independent selection of individuals
    • Random selection of individuals
    • Sufficiently large
  • In a random sample , each member of a population has an equal and independent chance of being selected.
  • Bias is a systematic discrepancy between estimates and the true population characteristic.
  • A sample of convenience is a collection of individuals that happen to be available at the time.
  • Sampling error
    • The difference between the estimate and average value of the estimate
  • Population parameters are constants whereas estimates are random variables , changing from one random sample to the next from the same population.
  • Larger samples on average will have smaller sampling error
  • Read: Chapters 1 & 2