Class Notes (811,170)
Canada (494,539)
Geography (947)
GGR270H1 (38)
Lecture 3

Lecture 3 - September 26.odt

4 Pages
Unlock Document

University of Toronto St. George
Damian Dupuy

Lecture 3 – September 26 Measures of the Centre – Mean – Most commonly used measure of central tendency – Sum of all values or observations divided by the number of observation Sample Population (check page check paper) Mean Example – the order of the numbers in the sample, its their value that they hold that matters Temperature Data: 7.3, 10.7, 9.1, 8.4, 13.9, 9.4, 8.2 =ADD them all up /7 =67/7= 9.57 (mean) = 9.6 (rounded up) (always round up based on the data you given, like the numbers above) Measures of the Centre 2 – Median – Value occupying the 'middle possition' in an ordered set of observations – with the median the value doesnt necessarly matter, its the value that occupies the middle possition. – Order the observations, lowest to highest, and find the middle position Formula: 0.5 (n+1) (this gives you the position) Median Example – Uneven Observation – Temperature Data: 7.3, 10.7, 9.1, 8.4, 13.9, 9.4, 8.2 Order: 7.3, 8.2, 8.4, 9.1, 9.4, 10.7, 13.9 Using formulth....... 0.5(7+1) = 4 position in the ordered set Therefore = 9.1 Median Example – Even Observations Temperature data: 7.3, 10.7, 9.1, 8.4, 13.9, 9.4, Order: 7.3, 8.2, 9.1, 9.4, 10.7, 13.9 Using Formula ..... 0.5 (6+1)=3.5 position in the ordered set So, add 3 and 4 and divide by 0.5 = 1/2 (9.1+9.4) = 1/2 (18.5)=9.25 Median Temperature is 9.25 Measure of the Centre 3 Mode – Value that occurs with the highest frequency – Allows you to locate the peak of a relative frequency histogram – Mode is 3 household members (based on the table presented) Choosing an Appropriate Measure – Mean is usually best measure as it is sensitive to change in a single observation – it is able to take the changes that can or might occur in the observation – it is also or can be the most represntative – however, it is not always a good measure, distribution by-mobil – it is not actually telling you that high peak – But not a good measure when... – Distribution is bi-modal (2 modes) – Skewed distributions Instead you can Use median It is good to use for normal graph Measures of the Centre 4 Normal – Mean, Median and Mode will be found in the middle Bimodal – Two modes – Mean and Median in the Middle Positively Skewed – Mode will always be to the LEFT – MEAN will always be to the RIGHT – because it is taking on-board the value of the outlier – Median will be somewhere in the middle Negatively Skewed – Mode will be on RIGHT – Mean will be on LEFT – Median will always b
More Less

Related notes for GGR270H1

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
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.