st: R: anova account for the same individuals

["Carlo Lazzaro" <carlo.lazzaro@tiscalinet.it>]

After two-way ANOVA, already recommended by other Statalisters have,  Liling
may want to go -contrast- (provided he gains access to Stata 12 at his
department. I am not sure that Stata 11.2 provides -contrast- as well).
Otherwise, Liling can keep it simpler with  one-way ANOVA followed by
multiple comparisons among rates.
I tried to replicate Liling's example from scratch with the following code:
-----------------------------code
begins----------------------------------------------
set obs 54
g group=_n in 1/54
g rate1=1*runiform()
g rate2=2*runiform()
g rate3=3*runiform()
g rate4=4*runiform()
g rate5=5*runiform()
g rate6=6*runiform()
g rate7=7*runiform()
g rate8=8*runiform()
reshape long rate, i(group) j(number)
anova rate group number  //all rate scores are stacked in rate variable;
number is the number of rates, ranging from 1 to 8                 
contrast number //  provided Liling gains access to Stata 12
oneway rate number, bonf // provided Liling cannot gain access to Stata 12
-----------------------------code
ends----------------------------------------------

Kind regards,
Carlo
-----Messaggio originale-----
Da: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] Per conto di HUANG, LILING
Inviato: martedì 19 novembre 2013 20:23
A: <statalist@hsphsun2.harvard.edu>
Oggetto: st: anova account for the same individuals

Dear Statalisters,
 
I have a group of people (n=54), rating eight different ads. So, I have 432
observations in a long format dataset. After I ran ANOVA on the rating
scores among ads (F (7, 424) = 13.37, p<0.001), I used pairwise comparisons
(tukey hsd) to test whether rating scores are significantly different
between ads. My question now is how I can account for the ratings come from
the same 54 people rather than from 432 people in this analysis since the
ratings from the same individual (id) among ads are dependent. Please let me
know how specify this in my syntax below. Or should I use other statistic
method?

anova score ad
tukeyhsd ad


Your prompt response to my inquiry will be greatly appreciated.

Liling Huang
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