Department

Geography

Course Code

GGR270H1

Professor

Damian Dupuy

GGR 270 – Lecture 3 – September 29, 2010

Statistics vs. Parameters

Graphs are limited in what they can tell us

Difficulty making inferences about a population when looking at a subset or sample

Therefore, we need to use numerical measures

Measures associated with the population are called parameters

Measures associated with a sample are called statistics

Measures of the centre

Mean:

Most commonly used measure of central tendency

Sum of all values or observations divided by the number of observations

Sample Population

Median:

Value occupying the ‘middle position’ in an ordered set of observations

Order the observations, lowest to highest, and find the middle position

www.notesolution.com

Expressed as: .5(n+1)

Mode:

Value that occurs with the highest frequency

Allows you to locate the peak of relative frequency histogram

Choosing appropriate measure

Mean is usually the best measure as it is sensitive to change in a single observation

Not a good measure when:

Distribution is bimodal

Skewed distribution

Outliers (extreme values) are present in the data set

Normal

Mean, Median, Mode

Bimodal

Mode, Mean, Median, Mode

Positive skew

mode, med, mean – mean>median

Negative skew

mean, median, mode – mean<median

*Mean always dragged in direction of skew

Measures of dispersion

www.notesolution.com

Over 90% improved by at least one letter grade.

OneClass has been such a huge help in my studies at UofT especially since I am a transfer student. OneClass is the study buddy I never had before and definitely gives me the extra push to get from a B to an A!

Leah — University of Toronto

Balancing social life With academics can be difficult, that is why I'm so glad that OneClass is out there where I can find the top notes for all of my classes. Now I can be the all-star student I want to be.

Saarim — University of Michigan

As a college student living on a college budget, I love how easy it is to earn gift cards just by submitting my notes.

Jenna — University of Wisconsin

OneClass has allowed me to catch up with my most difficult course! #lifesaver

Anne — University of California

Join OneClass

Access over 10 million pages of study

documents for 1.3 million courses.

Sign up

Join to view

OR

By registering, I agree to the
Terms
and
Privacy Policies

Already have an account?
Log in

Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.