Download - BIOL 300: Biostatistics
BIOL 300: Biostatistics
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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:
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
STATISTICS PAIRINGS
• 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
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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 coefficient2 testStandard deviation
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Sir Ronald Fisher
The Genetical Theory of Natural Selection
Founder of population genetics
Analysis of variance likelihood P-valuerandomized experiments multiple regressionetc., 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
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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
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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
Populations <-> Parameters;
Samples <-> Estimates
Nomenclature
Population
Parameters
Sample
Statistics
Mean Variance s2
Standard Deviatio
n
s€
x
Precise Imprecise
Biased
Unbiased
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