文档介绍：COMM 250 Agenda - Week 12
Housekeeping
RP2 Due Today – put it in your team’s folder
Lecture
Descriptive and Inferential Statistics
ITE12
Statistics
Why Study Statistics ?
Integral to the “Scientific Method”
Seeing the Forest Amid the Trees
Describing (Sports Statistics)
Inferring (Correlates of Cancer)
Predicting (Science, Business)
To Pursue an ‘Objective’ View
Statistics
Descriptive Statistics:
a way to summarize data
Inferential Statistics:
strategies for estimating population characteristics from data gathered on a sample
Descriptive Statistics
Measures of Central Tendency
Used to describe similarities among scores
What number best describes the entire distribution?
Measures of Dispersion
Used to describe differences among scores
How much do scores vary?
Inferential Statistics
Used For -
Estimation
To Extrapolate from a Sample to a Population
Significance Testing
To Determine the Importance of Observed Differences; ., Between Groups or Variables
Using Inferential Statistics for Estimation
Purpose
To Estimate (“Extrapolate”) from a Sample (Statistic) to a Population (Parameter)
Reason Why
It Saves Time and Money (Don’t Need to Survey/Measure the Entire Population)
A Statistic
Measure of a Sample (., Comm250) on Some Variable
., Average (Mean) Height m250 Students
A Parameter
A Characteristic of a Population (., Virginia)
., Average (Mean) Height of Residents of VA
Inferential Statistics
Note: When Statistics are Used for Estimation, this is the “Heart” of Using Statistics to Infer -
Statistic
Measure of a Sample (., HSers taking SAT in ‘02) on Some Variable
., Average (Mean) SAT score in 2002
., Average (Mean) SAT score Among GMU Freshmen
Parameter
A Characteristic of a Population (., All HSers Who Have Taken the SAT)
., Average (Mean) SAT Across ALL HSers (50 years?)
Parametric & Non-Parametric
Parametric Statistics
Stats Used to Establish Attributes of a Population Based on Attributes of a Sample
Non-Par