This preview shows page 1. Sign up to view the full content.
Unformatted text preview: = µi + ij
n = 45 women (all dog lovers)
where µi is the group i mean.
• If there’s only 2 levels, like in sex, then we
can use a twosample ttest H0 : µ1 = µ2.
• If we have more than 2 levels, we extend this
ttest idea to do a 1way ANOVA.
• A twosample ttest is essentially a 1way
ANOVA (it’s the simplest one, there’s only 2
levels to the factor) 3 Each woman randomly assigned to one of
three treatment groups as:
1) alone
2) with friend
3) with pet
Their heart rate is taken and recorded during
a stressful task.
Allen, Blascovich, Tomaka, Kelsey, 1988, Journal of Personality and Social Psychology. 4 > pets=read.csv("pets.csv") 100 > head(pets)
group
rate
1
P 69.169
2
F 99.692
3
P 70.169
4
C 80.369
5
C 87.446
6
P 75.985 > boxplot(rate~group) 80 90 ● > is.factor(group)
[1] TRUE 70 The treatment groups are:
‘C’ for control group or alone.
‘F’ for with friend.
‘P’ for with pet. 60 > attach(pets) Consider the distribution of heart rate by
treatment group... C F P > table(group)
group
CFP
15 15 15 This is a balanced 1way ANOVA since all
groups have the same number of subjects.
5 Get the mean of each group.
> tapply(rate,group,mean)
C
F
P
82.52407 91.32513 73.48307 If we consider µ1 as the population mean
heart rate of the control group,
µ2 as the population mean heart rate of the
friends group,
µ3 as the population mean heart rate of the
pet g...
View
Full
Document
This note was uploaded on 06/12/2013 for the course MATHEMATIC MAT7870 taught by Professor Sun during the Winter '13 term at Wayne State University.
 Winter '13
 Sun
 Statistics, Linear Regression, Variance

Click to edit the document details