Class Notes (836,653)
Canada (509,869)
SOAN 3120 (35)
Lecture

September 12.docx

4 Pages
110 Views
Unlock Document

Department
Sociology and Anthropology
Course
SOAN 3120
Professor
Michelle Dumas
Semester
Fall

Description
September 12, 2013 – Lecture 3 - SOAN Mean… - sigma represents the sum The Median - if n is an odd number, it’s integer – the easy way! - If n is an even number: fraction (average) o How to calculate:  Take the two middle numbers  Divide by two  That’s your median! Mean vs. Median - symmetric distribution (normal) o highest point is right in the middle - skewed distributions: the mean and the median are pulled in the direction of the skew o example: positive  mean will be larger than the median if it’s a positive skew o skewed right  the hill part is on the left, and the tail is on the right  median greater then the mean! o skewed left  the hill part is on the right, and the tail is on the left Measuring Spread: The Quartiles - how is dividied into quarters? - Quartiles are denoted with Qx - Q1: first quartile (represents ¼) - M (Q2): (1/2) o Second quartile is represented by the median (so Q2) o It’s the halfway point. - Q3: third quartile (3/4) o The point that has 75% or three quarters of the observations below it. Quartiles - finding Q1 and Q3 o order from smallest to largest o find median – the halfway point o find position - order observation - median use (n* = n/2) - position: (n+1)/2 September 12, 2013 – Lecture 3 - SOAN Example: - infant mortality o n=13, n*=6 o 13 17 21 / 22 22 24 //24 //39 42 45 / 46 58 66 - quartiles 1 and 3 o position: (6 +1)/2 = 3/5 o insert slide 20 here missed slide 21, 22, 23, 24 Boxplot - represents data of first and third quartile - draw a thick line where the median might be - draw whiskers o from the top max to the bottom minimum through the boxplot - this is to be a graphical representation of those 5 number summary - making a boxplot…………. o lay off scale to accommodate extremes of data o draw central box between q1 and q3 o draw median in central box o draw whisker from each extreme - outliers o some cases can be taken out o calculate inter-quartile range (IQR)  IQR = q3 – q1  Measure off 1.5 times the IQR  Fences  Observations between these fences are considered outliers  Most extreme non-outlying observation  These last of durations before the fence are called adjacent values  Whiskers: adjacent values Standrad deviation - the deviation from the mean - how far an observation
More Less

Related notes for SOAN 3120

Log In


OR

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?
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.


Submit