Upload
stian
View
61
Download
2
Tags:
Embed Size (px)
DESCRIPTION
Correlation and Linear Regression. Tools : S catterplot, correlation coefficient , linear regression. If two variables are somehow related, there would be some trend in the scatter plot. 1. Scatterplot. Scatterplot Q2. Scatterplot. Linearity; Direction ; Outlier. - PowerPoint PPT Presentation
Citation preview
Correlation and Linear Regression
Tools:Scatterplot, correlation coefficient,
linear regression
If two variables are somehow related, there would be some trend in the scatter plot.
1. Scatterplot1. Scatterplot
Scatterplot Q2Scatterplot Q2
Linearity; Direction; Outlier
ScatterplotScatterplot
Measure the strenght of the linear relationship of two variables.
Sign: + , - Magnitude: [-1,1]
Partial correlation
2. Correlation Coefficient2. Correlation Coefficient
•Pearson correlation
Correlation Coefficient Q3Correlation Coefficient Q3
Partial Correlation Coefficent
Assumptions: Error follows a normal distribution with mean
0 and constant standard deviation σ.
Error Or,
)|(
10
10
XY
XXY
Regression ModelRegression Model
Regression Q1 e)Regression Q1 e)
Regression OutputRegression Output
ZY 212.907.
:line Regression^
Q1 e) iii. Independent two-sample t test Q1 e) iii. Independent two-sample t test vs. t-test about the slope in regression vs. t-test about the slope in regression modelmodel
0:H testing
toequivalent is :H testingSo,
(Smoker) 1 Z; )(Nonsmoker 0Z
10
SmokerNonsmoker0
10Smoker
0Nonsmoker
10
ZY
Regression cont. Q4Regression cont. Q4
Check normality? same constant standard deviation?
Data Transform data Recode into different variables
Data Select cases
Analyze Descriptive Explore (QQ Plot)
Analyze Compare Means Independent samples t-test (One sided!)