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10 votes
1 answer
2k views

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 …
Jo Lewis's user avatar
  • 175
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. …
Darren James's user avatar
  • 1,261
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! …
Sarah Thomas's user avatar
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? …
timothy.s.lau's user avatar
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). …
user2338823's user avatar
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. …
statmerkur's user avatar
  • 6,650
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. …
ge36fiy's user avatar
  • 11
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. …
bluepole's user avatar
  • 2,779
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. …
Rachael Blake's user avatar
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 …
Mike Lawrence's user avatar
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 …
Doong's user avatar
  • 95
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 …
user231906's user avatar
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 …
Andre Dorini's user avatar
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. …
deasmhumnha's user avatar
  • 1,079
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? …
user2925716's user avatar

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