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10
votes
1
answer
2k
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Type III sums of squares
And now I have Type III sums of squares for $A$, $B$, and their interaction (A:B) using drop1(model, .~., test="F").
What I am stuck with is how sums of squares is calculated for $B$. … predB<-predict(lm(y~A+A:B))
sum((predFull-predB)^2)
#Sums of squares should be 0.15075 (according to anova table)
#but calculated to be 2.5e-31
#SS(AB|A,B)
predAB<-predict(lm(y~A+B))
sum((predFull-predAB …
3
votes
0
answers
267
views
Interpretation of default Type III Sums in Squares in R
One way to
obtain the "correct" Type III sums of squares is to change the model parameterization to sum coding, "contr.sum". … III Sums of Squares produced under sum coding
These correctly match the Type I Sums of Squares for this balanced case. …
2
votes
2
answers
2k
views
Mixed Model Type-III Sums of Squares- R vs SPSS
I am trying to replicate output in SPSS, that was computed using Type 3 Sums of Squares, in R. … Can someone help me get Type 3 Sums of Squares for a mixed model in R?
Thank you! …
2
votes
0
answers
299
views
Explain the difference between type 1,2,3,4 sums of squares
Can someone explain the difference between type 1:4 sums of squares using examples with relatable variables? …
1
vote
1
answer
239
views
Main effect after accounting for interaction - Type III Sums of Squares
I am trying to understand Type I/II/III sums of squares.
Take for instance the 2 way Anova with 2 factors A and B.
I do not follow what Type III Sums of Squares are. … In type III sums of squares we account for the main effect (say A) AFTER removing the effect of the other main effect(B) + interaction(AB). …
3
votes
2
answers
795
views
Why do type III sums of squares require orthogonal contrasts?
I have read many times that one has to set orthogonal contrast to get correct type III sums of square. E.g. … John Fox says
To compute Type-III tests using incremental F-tests, one needs
contrasts that are orthogonal in the row-basis of the model matrix. …
1
vote
1
answer
398
views
Which type of sums of squares does lm-function in R use?
I ran a two-way ANCOVA in R:
ancova = lm(DV ~ IV1*IV2 + CV1 + CV2 + CV3, data = Data)
summary.aov(ancova)
Anybody know if this uses type III sums of squares? … I know that the anova() and aov() functions use type I, but I am trying to get type III. …
2
votes
1
answer
40
views
How to resolve confusing ANOVA results using type II sums of squares?
Performing a 2 x 2 ANOVA with type II sums of squares:
aov_car(value ~ treatment * gender + Error(id), data=dd, type=2)
yields the following results:
Effect df MSE F ges p.value … II sums of squares imply that they are assessed independently, without the inclusion of their interaction treatment:gender. …
1
vote
0
answers
366
views
A-priori contrasts with type III sums of squares in R
I have a statistical analysis / data analysis problem:
I am analyzing data using a factorial three-way ANOVA with a-priori contrasts and type III sums of squares. … (Please don't speak about type I SS vs. type III SS. That's not the point of my question.) I get the contrasts like I need using summary.aov(), however that uses type I SS. …
17
votes
4
answers
5k
views
Should I include an argument to request type-III sums of squares in ezANOVA?
The ezANOVA() function mostly serves as a wrapper to car::Anova(), but the current version of ezANOVA() implements only type-II sums of squares, whereas car::Anova() permits specification of either type-II … Reasons for not including a "SS_type" argument in ezANOVA():
The difference between type I, II, and III sum squares only crops up when data are unbalanced, in which case I'd say that more benefit is …
9
votes
1
answer
387
views
Why is it rarely reported in papers which type of sums of squares is used in Anova results?
Following my short experience in statistics, it seems that the type of sums of squares (type I,II,III,IV...) used in getting ANOVA results could make a dramatic difference in test results (especially of …
2
votes
1
answer
310
views
Two way ANOVA, no difference between tests based on type I vs type II sums of squares
library(car)
> anova(res.aov3) # type I
Analysis of Variance Table
Response: len
Df Sum Sq Mean Sq F value Pr(>F)
supp 1 205.35 205.35 15.572 0.0002312 ***
dose 2 2426.43 … =2) # type II
Anova Table (Type II tests)
Response: len
Sum Sq Df F value Pr(>F)
supp 205.35 1 15.572 0.0002312 ***
dose 2426.43 2 92.000 < 2.2e-16 ***
supp:dose 108.32 …
1
vote
0
answers
167
views
2x2 Repeated measures ANOVA gives DIFFERENT result in R and SPSS? (Same type of sums/data/an...
My design is balanced, and I use the same type of sums of squares (Type 3) in both analysis, but still get different F-ratios. Anyone know why? … (VCondition, Stimulus), type =3)
and here is the output:
$ANOVA
Effect DFn DFd F p p<.05
2 VCondition 1 81 0.006498711 0.945754134 …
5
votes
2
answers
519
views
R: Why does type III ANOVA require contrasts that sum to zero?
The key seems to be the coding of the variable interaction (and vs. xor for treatment vs. sum). … When I compare the full model (~ A*B) with a model including only B and xor(A,B), I get the "correct" difference in the sums of squared residuals for A, regardless of the type of contrasts used. …
4
votes
3
answers
6k
views
Is there a constraint on the sum of the type-I & type II error probabilities?
Is it true that if $H_0$ and $H_a$ are complementary hypotheses of the Binomial trial, i.e., the negation of $H_0$ is $H_a$ then the type-I error $\alpha$ plus type-II error $\beta$ equals 1? … Or is that sum always less then 1, or can it be sometimes even greater then 1? …