BIOL 300: BiostatisticsStatistical 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: harmon@zoology.ubc.ca

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

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

Populations <-> Parameters;

Samples <-> Estimates

Nomenclature

s"Standard

Deviation

s2"2Variance

µMean

Sample

Statistics

Population

Parameters

!

x

Precise Imprecise

Biased

Unbiased

Properties of a good sample

• Independent selection of individuals

• Random selection of individuals

• Sufficiently large

In a random sample, eachmember of a population hasan equal and independentchance of being selected.

Bias is a systematicdiscrepancy betweenestimates and the true

population characteristic.

A sample of convenience is acollection of individuals that

happen to be available at thetime.

Sampling error

• The difference between the estimate and

average value of the estimate

Population parameters areconstants whereas estimates

are random variables,changing from one randomsample to the next from the

same population.

Larger samples on average will

have smaller sampling errorRead: Chapters 1 & 2